My daughter's math problem

[simoneandrews]

My daughter is doing the Please Excuse My Dear Aunt Sally method to solving a problem (parenthesis exponents multplication division addition and subtraction). We think her answer, 1 might be wrong but can't figure out why. Here's the problem

20 - 4[suphx8ijwv]2[/suphx8ijwv] - 3 + 6

heres the work...
20-16-3+6
20 - 16 (-3)
4-3
1

thanks for the help.

 

[chrisr]

Given that there are no parenthesis (paranthesis placed in different ways yields different answers),
this sum is

20-(4[sup:jo5hgkbt]2[/sup:jo5hgkbt])-3+6

= 20-16+6-3 = 4+6-3 = 7.

20-(4[sup:jo5hgkbt]2[/sup:jo5hgkbt]-3) + 6 is different.

You've calculated (20-4[sup:jo5hgkbt]2[/sup:jo5hgkbt])-(6-3)

 

[Loren]

Please Excuse My Dear Aunt Sally

Many times students get confused because they interpret this mnemonic device as
parenthesis, exponents, multiplication, division, addition, and subtraction TO BE DONE IN THAT ORDER. That is what is in error. It really says this.

P - Parenthesis AND other grouping symbols. Perform operations within the grouping symbols following the order of operations.

E - Exponents and radicals.

M and D - Perform multiplication and division in the order they appear (from left to right) in the problem. (Some students do all the multiplication first, then all the division. This is wrong. In the problem 4 X 3 ÷ 2 X 2 becomes 12 ÷ 2 X 2 = 6 X 2 = 12 NOT 12 ÷ 4 = 3.)

A and S - Perform addition and subtraction in the order they appear (from left to right) in the problem.