Now, for the E in PEMDAS...

E stands for "exponents" like

2^3

 

PEMDAS...  E = Exponents...  MD = Multiplication & Division...  AS = Addition & Subtraction

Do exponents before multiplication & division and addition & subtraction.

So, in a problem like this:

15 - 2^3
 

Do the exponent first:

15 - 2^3 = 15 - 8 = 7

Don't do this!
15 - 2^3  does not equal  13^3