Mixing
9-4+1 does not equal to 4?
Clash Royale CLAN TAG#URR8PPP
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I ran across the following math problem where there is arithmetic involved:
$$9-4+1$$
Where supposedly the answer is 6? I entered into my computer and calculator and got the same result so I realized there was something strange in this math problem because it does not follow the PEMDAS pattern.
Can someone explain to me why the answer is equal to 6 and not 4?.
arithmetic
asked 55 mins ago
ac1002
184
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
2
down vote
favorite
I ran across the following math problem where there is arithmetic involved:
$$9-4+1$$
Where supposedly the answer is 6? I entered into my computer and calculator and got the same result so I realized there was something strange in this math problem because it does not follow the PEMDAS pattern.
Can someone explain to me why the answer is equal to 6 and not 4?.
arithmetic
asked 55 mins ago
ac1002
184
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
PE(MD)(AS) is the actual rule.
– Randall
54 mins ago
Can you be more specific?. Can you show some examples?.
– ac1002
53 mins ago
The order of addition and subtraction goes from left to right. In this case subtraction is first then addition.
– Phil H
46 mins ago
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
I ran across the following math problem where there is arithmetic involved:
$$9-4+1$$
Where supposedly the answer is 6? I entered into my computer and calculator and got the same result so I realized there was something strange in this math problem because it does not follow the PEMDAS pattern.
Can someone explain to me why the answer is equal to 6 and not 4?.
arithmetic
asked 55 mins ago
ac1002
184
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I ran across the following math problem where there is arithmetic involved:
$$9-4+1$$
Where supposedly the answer is 6? I entered into my computer and calculator and got the same result so I realized there was something strange in this math problem because it does not follow the PEMDAS pattern.
Can someone explain to me why the answer is equal to 6 and not 4?.
arithmetic
arithmetic
asked 55 mins ago
ac1002
184
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 55 mins ago
ac1002
184
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 55 mins ago
ac1002
184
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 55 mins ago
ac1002
184
asked 55 mins ago
ac1002
184
184
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
ac1002 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
PE(MD)(AS) is the actual rule.
– Randall
54 mins ago
Can you be more specific?. Can you show some examples?.
– ac1002
53 mins ago
The order of addition and subtraction goes from left to right. In this case subtraction is first then addition.
– Phil H
46 mins ago
add a comment |Â
PE(MD)(AS) is the actual rule.
– Randall
54 mins ago
Can you be more specific?. Can you show some examples?.
– ac1002
53 mins ago
The order of addition and subtraction goes from left to right. In this case subtraction is first then addition.
– Phil H
46 mins ago
PE(MD)(AS) is the actual rule.
– Randall
54 mins ago
PE(MD)(AS) is the actual rule.
– Randall
54 mins ago
Can you be more specific?. Can you show some examples?.
– ac1002
53 mins ago
Can you be more specific?. Can you show some examples?.
– ac1002
53 mins ago
The order of addition and subtraction goes from left to right. In this case subtraction is first then addition.
– Phil H
46 mins ago
The order of addition and subtraction goes from left to right. In this case subtraction is first then addition.
– Phil H
46 mins ago
add a comment |Â
4 Answers
4
active
oldest
votes
up vote
2
down vote
Probably getting too abstract... but subtraction doesn't really exist. What we are really doing when we subtract is adding a negative number.
$9 + (-4) + 1 = 6$
Once we have it in the this form, then we can do our addition in any order.
$(9 + (-4)) + 1 = 5+1 = 6\
(9 + ((-4) + 1) = 9+(-3) = 6$
That is addition is associative.
And we can even swap it around. Addition is commutative.
$9 + 1 + (-4) = 10+(-4) = 6$
In many ways "PEMDAS" creates more confusion and problems than it is worth.
answered 47 mins ago
Doug M
41.1k31751
Can you show me an example on how you could do the problem with multiplication and division?.
– ac1002
35 mins ago
Multiplication distributes over addition. Keep that straight and the rest takes care of itself. $frac 5(2 + 4)2 - 6cdot frac 72 + 13 = 5(3) + 7(3) + 13 = 12(3) + 13 = 49$
– Doug M
9 mins ago
add a comment |Â
up vote
1
down vote
Working from the left to the right,$$9-4+1= (9-4)+1=5+1=6$$
answered 53 mins ago
Siong Thye Goh
88.4k1460111
You always work from the left to the right?.
– ac1002
52 mins ago
when it comes to addition and subtraction, yes, from the left to the right.
– Siong Thye Goh
50 mins ago
Only for addition and subtraction?.
– ac1002
49 mins ago
Do things in Parentheses First, (Powers, Roots) before Multiply, Divide, Add or Subtract, (Multiply or Divide) before you (Add or Subtract), Otherwise just go left to right. That's what PEMDAS says.
– Siong Thye Goh
46 mins ago
add a comment |Â
up vote
1
down vote
Your confusion lies in thinking that Addition supersedes Subtraction. The actual precedence set by "PEMDAS" is
- Parenthetical terms first
- Exponents
- Any multiplication OR division (equal precedence!)
- Any addition OR subtraction (equal precedence!)
This is why I suggested you think of it as PE(MD)(AS).
This is nothing more than a convenient agreement and not some mysterious law of nature. It allows us to write $3x-y$ without ambiguity, as it means $(3x)-y$ and not $3(x-y)$. If we mean the latter, we have to say it.
So, for example,
$$
5cdot 3 -2= 15-2=13
$$
and NOT $5 cdot 3-2=5$. If I wanted the latter I have to bracket it off to make it respect PEMDAS: $5cdot (3-2) = 5 cdot 1 =5$.
In general, when a "tie" in precedence comes, we operate left-to-right. For your case, $9-4+1=5+1=6$ since the subtraction is done first. You gave the second (addition) precedence, when really the subtraction gets done first, since they have equal precedence and the left-most one comes first.
To be honest, even this is sort of rigid. I can even do your addition first, as long as I respect the minus sign the right way. For instance
$$
9 - 4 + 1 = 9 + (-4+1) = 9 + (-3) = 9-3 =6.
$$
For some other examples,
$$
7+4-5+6= 11-5+6=6+6=12
$$
and
$$
2cdot 5 - 7 cdot 3 + 4 = 10 - 21 + 4 = -11 + 4 = -7.
$$
answered 42 mins ago
Randall
8,0451927
add a comment |Â
up vote
0
down vote
"PEMDAS" does not mean addition comes before subtraction. In fact addition and subtraction are done from left to right (unless modified by brackets).
So for your problem, first do $9-4=5$, then $5+1=6$.
This is an excellent illustration of why people should not rely on memorisation without understanding!
answered 52 mins ago
David
66.6k663125
So you solve the math problem from the left to right only when addition and subtraction are involved, or always despite the arithmetic symbol?.
– ac1002
50 mins ago
Same thing goes for multiplication and division - left to right. However multiplication and division come before addition and subtraction. For example $$5+4times3div2-1=5+12div2-1=5+6-1=11-1=10 .$$ It is often a good idea to insert brackets for clarity, even if they are not strictly necessary. The above could be written $$5+(4times3div2)-1 .$$
– David
44 mins ago
add a comment |Â
4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
Probably getting too abstract... but subtraction doesn't really exist. What we are really doing when we subtract is adding a negative number.
$9 + (-4) + 1 = 6$
Once we have it in the this form, then we can do our addition in any order.
$(9 + (-4)) + 1 = 5+1 = 6\
(9 + ((-4) + 1) = 9+(-3) = 6$
That is addition is associative.
And we can even swap it around. Addition is commutative.
$9 + 1 + (-4) = 10+(-4) = 6$
In many ways "PEMDAS" creates more confusion and problems than it is worth.
answered 47 mins ago
Doug M
41.1k31751
Can you show me an example on how you could do the problem with multiplication and division?.
– ac1002
35 mins ago
Multiplication distributes over addition. Keep that straight and the rest takes care of itself. $frac 5(2 + 4)2 - 6cdot frac 72 + 13 = 5(3) + 7(3) + 13 = 12(3) + 13 = 49$
– Doug M
9 mins ago
add a comment |Â
up vote
2
down vote
Probably getting too abstract... but subtraction doesn't really exist. What we are really doing when we subtract is adding a negative number.
$9 + (-4) + 1 = 6$
Once we have it in the this form, then we can do our addition in any order.
$(9 + (-4)) + 1 = 5+1 = 6\
(9 + ((-4) + 1) = 9+(-3) = 6$
That is addition is associative.
And we can even swap it around. Addition is commutative.
$9 + 1 + (-4) = 10+(-4) = 6$
In many ways "PEMDAS" creates more confusion and problems than it is worth.
answered 47 mins ago
Doug M
41.1k31751
Can you show me an example on how you could do the problem with multiplication and division?.
– ac1002
35 mins ago
Multiplication distributes over addition. Keep that straight and the rest takes care of itself. $frac 5(2 + 4)2 - 6cdot frac 72 + 13 = 5(3) + 7(3) + 13 = 12(3) + 13 = 49$
– Doug M
9 mins ago
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Probably getting too abstract... but subtraction doesn't really exist. What we are really doing when we subtract is adding a negative number.
$9 + (-4) + 1 = 6$
Once we have it in the this form, then we can do our addition in any order.
$(9 + (-4)) + 1 = 5+1 = 6\
(9 + ((-4) + 1) = 9+(-3) = 6$
That is addition is associative.
And we can even swap it around. Addition is commutative.
$9 + 1 + (-4) = 10+(-4) = 6$
In many ways "PEMDAS" creates more confusion and problems than it is worth.
answered 47 mins ago
Doug M
41.1k31751
Probably getting too abstract... but subtraction doesn't really exist. What we are really doing when we subtract is adding a negative number.
$9 + (-4) + 1 = 6$
Once we have it in the this form, then we can do our addition in any order.
$(9 + (-4)) + 1 = 5+1 = 6\
(9 + ((-4) + 1) = 9+(-3) = 6$
That is addition is associative.
And we can even swap it around. Addition is commutative.
$9 + 1 + (-4) = 10+(-4) = 6$
In many ways "PEMDAS" creates more confusion and problems than it is worth.
answered 47 mins ago
Doug M
41.1k31751
answered 47 mins ago
Doug M
41.1k31751
answered 47 mins ago
Doug M
41.1k31751
answered 47 mins ago
Doug M
41.1k31751
41.1k31751
Can you show me an example on how you could do the problem with multiplication and division?.
– ac1002
35 mins ago
Multiplication distributes over addition. Keep that straight and the rest takes care of itself. $frac 5(2 + 4)2 - 6cdot frac 72 + 13 = 5(3) + 7(3) + 13 = 12(3) + 13 = 49$
– Doug M
9 mins ago
add a comment |Â
Can you show me an example on how you could do the problem with multiplication and division?.
– ac1002
35 mins ago
Multiplication distributes over addition. Keep that straight and the rest takes care of itself. $frac 5(2 + 4)2 - 6cdot frac 72 + 13 = 5(3) + 7(3) + 13 = 12(3) + 13 = 49$
– Doug M
9 mins ago
Can you show me an example on how you could do the problem with multiplication and division?.
– ac1002
35 mins ago
Can you show me an example on how you could do the problem with multiplication and division?.
– ac1002
35 mins ago
Multiplication distributes over addition. Keep that straight and the rest takes care of itself. $frac 5(2 + 4)2 - 6cdot frac 72 + 13 = 5(3) + 7(3) + 13 = 12(3) + 13 = 49$
– Doug M
9 mins ago
Multiplication distributes over addition. Keep that straight and the rest takes care of itself. $frac 5(2 + 4)2 - 6cdot frac 72 + 13 = 5(3) + 7(3) + 13 = 12(3) + 13 = 49$
– Doug M
9 mins ago
add a comment |Â
up vote
1
down vote
Working from the left to the right,$$9-4+1= (9-4)+1=5+1=6$$
answered 53 mins ago
Siong Thye Goh
88.4k1460111
You always work from the left to the right?.
– ac1002
52 mins ago
when it comes to addition and subtraction, yes, from the left to the right.
– Siong Thye Goh
50 mins ago
Only for addition and subtraction?.
– ac1002
49 mins ago
Do things in Parentheses First, (Powers, Roots) before Multiply, Divide, Add or Subtract, (Multiply or Divide) before you (Add or Subtract), Otherwise just go left to right. That's what PEMDAS says.
– Siong Thye Goh
46 mins ago
add a comment |Â
up vote
1
down vote
Working from the left to the right,$$9-4+1= (9-4)+1=5+1=6$$
answered 53 mins ago
Siong Thye Goh
88.4k1460111
You always work from the left to the right?.
– ac1002
52 mins ago
when it comes to addition and subtraction, yes, from the left to the right.
– Siong Thye Goh
50 mins ago
Only for addition and subtraction?.
– ac1002
49 mins ago
Do things in Parentheses First, (Powers, Roots) before Multiply, Divide, Add or Subtract, (Multiply or Divide) before you (Add or Subtract), Otherwise just go left to right. That's what PEMDAS says.
– Siong Thye Goh
46 mins ago
add a comment |Â
up vote
1
down vote
up vote
1
down vote
Working from the left to the right,$$9-4+1= (9-4)+1=5+1=6$$
answered 53 mins ago
Siong Thye Goh
88.4k1460111
Working from the left to the right,$$9-4+1= (9-4)+1=5+1=6$$
answered 53 mins ago
Siong Thye Goh
88.4k1460111
answered 53 mins ago
Siong Thye Goh
88.4k1460111
answered 53 mins ago
Siong Thye Goh
88.4k1460111
answered 53 mins ago
Siong Thye Goh
88.4k1460111
88.4k1460111
You always work from the left to the right?.
– ac1002
52 mins ago
when it comes to addition and subtraction, yes, from the left to the right.
– Siong Thye Goh
50 mins ago
Only for addition and subtraction?.
– ac1002
49 mins ago
Do things in Parentheses First, (Powers, Roots) before Multiply, Divide, Add or Subtract, (Multiply or Divide) before you (Add or Subtract), Otherwise just go left to right. That's what PEMDAS says.
– Siong Thye Goh
46 mins ago
add a comment |Â
You always work from the left to the right?.
– ac1002
52 mins ago
when it comes to addition and subtraction, yes, from the left to the right.
– Siong Thye Goh
50 mins ago
Only for addition and subtraction?.
– ac1002
49 mins ago
Do things in Parentheses First, (Powers, Roots) before Multiply, Divide, Add or Subtract, (Multiply or Divide) before you (Add or Subtract), Otherwise just go left to right. That's what PEMDAS says.
– Siong Thye Goh
46 mins ago
You always work from the left to the right?.
– ac1002
52 mins ago
You always work from the left to the right?.
– ac1002
52 mins ago
when it comes to addition and subtraction, yes, from the left to the right.
– Siong Thye Goh
50 mins ago
when it comes to addition and subtraction, yes, from the left to the right.
– Siong Thye Goh
50 mins ago
Only for addition and subtraction?.
– ac1002
49 mins ago
Only for addition and subtraction?.
– ac1002
49 mins ago
Do things in Parentheses First, (Powers, Roots) before Multiply, Divide, Add or Subtract, (Multiply or Divide) before you (Add or Subtract), Otherwise just go left to right. That's what PEMDAS says.
– Siong Thye Goh
46 mins ago
Do things in Parentheses First, (Powers, Roots) before Multiply, Divide, Add or Subtract, (Multiply or Divide) before you (Add or Subtract), Otherwise just go left to right. That's what PEMDAS says.
– Siong Thye Goh
46 mins ago
add a comment |Â
up vote
1
down vote
Your confusion lies in thinking that Addition supersedes Subtraction. The actual precedence set by "PEMDAS" is
- Parenthetical terms first
- Exponents
- Any multiplication OR division (equal precedence!)
- Any addition OR subtraction (equal precedence!)
This is why I suggested you think of it as PE(MD)(AS).
This is nothing more than a convenient agreement and not some mysterious law of nature. It allows us to write $3x-y$ without ambiguity, as it means $(3x)-y$ and not $3(x-y)$. If we mean the latter, we have to say it.
So, for example,
$$
5cdot 3 -2= 15-2=13
$$
and NOT $5 cdot 3-2=5$. If I wanted the latter I have to bracket it off to make it respect PEMDAS: $5cdot (3-2) = 5 cdot 1 =5$.
In general, when a "tie" in precedence comes, we operate left-to-right. For your case, $9-4+1=5+1=6$ since the subtraction is done first. You gave the second (addition) precedence, when really the subtraction gets done first, since they have equal precedence and the left-most one comes first.
To be honest, even this is sort of rigid. I can even do your addition first, as long as I respect the minus sign the right way. For instance
$$
9 - 4 + 1 = 9 + (-4+1) = 9 + (-3) = 9-3 =6.
$$
For some other examples,
$$
7+4-5+6= 11-5+6=6+6=12
$$
and
$$
2cdot 5 - 7 cdot 3 + 4 = 10 - 21 + 4 = -11 + 4 = -7.
$$
answered 42 mins ago
Randall
8,0451927
add a comment |Â
up vote
1
down vote
Your confusion lies in thinking that Addition supersedes Subtraction. The actual precedence set by "PEMDAS" is
- Parenthetical terms first
- Exponents
- Any multiplication OR division (equal precedence!)
- Any addition OR subtraction (equal precedence!)
This is why I suggested you think of it as PE(MD)(AS).
This is nothing more than a convenient agreement and not some mysterious law of nature. It allows us to write $3x-y$ without ambiguity, as it means $(3x)-y$ and not $3(x-y)$. If we mean the latter, we have to say it.
So, for example,
$$
5cdot 3 -2= 15-2=13
$$
and NOT $5 cdot 3-2=5$. If I wanted the latter I have to bracket it off to make it respect PEMDAS: $5cdot (3-2) = 5 cdot 1 =5$.
In general, when a "tie" in precedence comes, we operate left-to-right. For your case, $9-4+1=5+1=6$ since the subtraction is done first. You gave the second (addition) precedence, when really the subtraction gets done first, since they have equal precedence and the left-most one comes first.
To be honest, even this is sort of rigid. I can even do your addition first, as long as I respect the minus sign the right way. For instance
$$
9 - 4 + 1 = 9 + (-4+1) = 9 + (-3) = 9-3 =6.
$$
For some other examples,
$$
7+4-5+6= 11-5+6=6+6=12
$$
and
$$
2cdot 5 - 7 cdot 3 + 4 = 10 - 21 + 4 = -11 + 4 = -7.
$$
answered 42 mins ago
Randall
8,0451927
add a comment |Â
up vote
1
down vote
up vote
1
down vote
Your confusion lies in thinking that Addition supersedes Subtraction. The actual precedence set by "PEMDAS" is
- Parenthetical terms first
- Exponents
- Any multiplication OR division (equal precedence!)
- Any addition OR subtraction (equal precedence!)
This is why I suggested you think of it as PE(MD)(AS).
This is nothing more than a convenient agreement and not some mysterious law of nature. It allows us to write $3x-y$ without ambiguity, as it means $(3x)-y$ and not $3(x-y)$. If we mean the latter, we have to say it.
So, for example,
$$
5cdot 3 -2= 15-2=13
$$
and NOT $5 cdot 3-2=5$. If I wanted the latter I have to bracket it off to make it respect PEMDAS: $5cdot (3-2) = 5 cdot 1 =5$.
In general, when a "tie" in precedence comes, we operate left-to-right. For your case, $9-4+1=5+1=6$ since the subtraction is done first. You gave the second (addition) precedence, when really the subtraction gets done first, since they have equal precedence and the left-most one comes first.
To be honest, even this is sort of rigid. I can even do your addition first, as long as I respect the minus sign the right way. For instance
$$
9 - 4 + 1 = 9 + (-4+1) = 9 + (-3) = 9-3 =6.
$$
For some other examples,
$$
7+4-5+6= 11-5+6=6+6=12
$$
and
$$
2cdot 5 - 7 cdot 3 + 4 = 10 - 21 + 4 = -11 + 4 = -7.
$$
answered 42 mins ago
Randall
8,0451927
Your confusion lies in thinking that Addition supersedes Subtraction. The actual precedence set by "PEMDAS" is
- Parenthetical terms first
- Exponents
- Any multiplication OR division (equal precedence!)
- Any addition OR subtraction (equal precedence!)
This is why I suggested you think of it as PE(MD)(AS).
This is nothing more than a convenient agreement and not some mysterious law of nature. It allows us to write $3x-y$ without ambiguity, as it means $(3x)-y$ and not $3(x-y)$. If we mean the latter, we have to say it.
So, for example,
$$
5cdot 3 -2= 15-2=13
$$
and NOT $5 cdot 3-2=5$. If I wanted the latter I have to bracket it off to make it respect PEMDAS: $5cdot (3-2) = 5 cdot 1 =5$.
In general, when a "tie" in precedence comes, we operate left-to-right. For your case, $9-4+1=5+1=6$ since the subtraction is done first. You gave the second (addition) precedence, when really the subtraction gets done first, since they have equal precedence and the left-most one comes first.
To be honest, even this is sort of rigid. I can even do your addition first, as long as I respect the minus sign the right way. For instance
$$
9 - 4 + 1 = 9 + (-4+1) = 9 + (-3) = 9-3 =6.
$$
For some other examples,
$$
7+4-5+6= 11-5+6=6+6=12
$$
and
$$
2cdot 5 - 7 cdot 3 + 4 = 10 - 21 + 4 = -11 + 4 = -7.
$$
answered 42 mins ago
Randall
8,0451927
edited 29 mins ago
answered 42 mins ago
Randall
8,0451927
answered 42 mins ago
Randall
8,0451927
answered 42 mins ago
Randall
8,0451927
8,0451927
add a comment |Â
add a comment |Â
up vote
0
down vote
"PEMDAS" does not mean addition comes before subtraction. In fact addition and subtraction are done from left to right (unless modified by brackets).
So for your problem, first do $9-4=5$, then $5+1=6$.
This is an excellent illustration of why people should not rely on memorisation without understanding!
answered 52 mins ago
David
66.6k663125
So you solve the math problem from the left to right only when addition and subtraction are involved, or always despite the arithmetic symbol?.
– ac1002
50 mins ago
Same thing goes for multiplication and division - left to right. However multiplication and division come before addition and subtraction. For example $$5+4times3div2-1=5+12div2-1=5+6-1=11-1=10 .$$ It is often a good idea to insert brackets for clarity, even if they are not strictly necessary. The above could be written $$5+(4times3div2)-1 .$$
– David
44 mins ago
add a comment |Â
up vote
0
down vote
"PEMDAS" does not mean addition comes before subtraction. In fact addition and subtraction are done from left to right (unless modified by brackets).
So for your problem, first do $9-4=5$, then $5+1=6$.
This is an excellent illustration of why people should not rely on memorisation without understanding!
answered 52 mins ago
David
66.6k663125
So you solve the math problem from the left to right only when addition and subtraction are involved, or always despite the arithmetic symbol?.
– ac1002
50 mins ago
Same thing goes for multiplication and division - left to right. However multiplication and division come before addition and subtraction. For example $$5+4times3div2-1=5+12div2-1=5+6-1=11-1=10 .$$ It is often a good idea to insert brackets for clarity, even if they are not strictly necessary. The above could be written $$5+(4times3div2)-1 .$$
– David
44 mins ago
add a comment |Â
up vote
0
down vote
up vote
0
down vote
"PEMDAS" does not mean addition comes before subtraction. In fact addition and subtraction are done from left to right (unless modified by brackets).
So for your problem, first do $9-4=5$, then $5+1=6$.
This is an excellent illustration of why people should not rely on memorisation without understanding!
answered 52 mins ago
David
66.6k663125
"PEMDAS" does not mean addition comes before subtraction. In fact addition and subtraction are done from left to right (unless modified by brackets).
So for your problem, first do $9-4=5$, then $5+1=6$.
This is an excellent illustration of why people should not rely on memorisation without understanding!
answered 52 mins ago
David
66.6k663125
answered 52 mins ago
David
66.6k663125
answered 52 mins ago
David
66.6k663125
answered 52 mins ago
David
66.6k663125
66.6k663125
So you solve the math problem from the left to right only when addition and subtraction are involved, or always despite the arithmetic symbol?.
– ac1002
50 mins ago
Same thing goes for multiplication and division - left to right. However multiplication and division come before addition and subtraction. For example $$5+4times3div2-1=5+12div2-1=5+6-1=11-1=10 .$$ It is often a good idea to insert brackets for clarity, even if they are not strictly necessary. The above could be written $$5+(4times3div2)-1 .$$
– David
44 mins ago
add a comment |Â
So you solve the math problem from the left to right only when addition and subtraction are involved, or always despite the arithmetic symbol?.
– ac1002
50 mins ago
Same thing goes for multiplication and division - left to right. However multiplication and division come before addition and subtraction. For example $$5+4times3div2-1=5+12div2-1=5+6-1=11-1=10 .$$ It is often a good idea to insert brackets for clarity, even if they are not strictly necessary. The above could be written $$5+(4times3div2)-1 .$$
– David
44 mins ago
So you solve the math problem from the left to right only when addition and subtraction are involved, or always despite the arithmetic symbol?.
– ac1002
50 mins ago
So you solve the math problem from the left to right only when addition and subtraction are involved, or always despite the arithmetic symbol?.
– ac1002
50 mins ago
Same thing goes for multiplication and division - left to right. However multiplication and division come before addition and subtraction. For example $$5+4times3div2-1=5+12div2-1=5+6-1=11-1=10 .$$ It is often a good idea to insert brackets for clarity, even if they are not strictly necessary. The above could be written $$5+(4times3div2)-1 .$$
– David
44 mins ago
Same thing goes for multiplication and division - left to right. However multiplication and division come before addition and subtraction. For example $$5+4times3div2-1=5+12div2-1=5+6-1=11-1=10 .$$ It is often a good idea to insert brackets for clarity, even if they are not strictly necessary. The above could be written $$5+(4times3div2)-1 .$$
– David
44 mins ago
add a comment |Â
ac1002 is a new contributor. Be nice, and check out our Code of Conduct.
ac1002 is a new contributor. Be nice, and check out our Code of Conduct.
ac1002 is a new contributor. Be nice, and check out our Code of Conduct.
ac1002 is a new contributor. Be nice, and check out our Code of Conduct.
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PE(MD)(AS) is the actual rule.
– Randall
54 mins ago
Can you be more specific?. Can you show some examples?.
– ac1002
53 mins ago
The order of addition and subtraction goes from left to right. In this case subtraction is first then addition.
– Phil H
46 mins ago