PEMDAS question

Question

my group and I are having a hard time with the PEMDAS problem 20/2(5+5) half of us say its 100 but the other half is saying 1.

Answer 1

The 100 team is correct.

 

Do the parentheses first, so it becomes 20 ÷ 2 x 10.

 

Division and multiplication are in the same pairing, so you go left to right. Even though the acronym PEMDAS seems to say that you would always do the multiplication first, it actually means "do all multiplication and/or division before you do any addition and/or subtraction."

 

I hope that makes sense. :-)

 

Matt in NY

Answer 2

PEMDAS:

P = operations within Parentheses

E = Exponents (including radicals)

M = Multiplications

D = Divisions

A = Additions

S = Subtractions

 

20/2(5+5)

 

The confusion here is whether the problem is:

 

20*(5+5)                              20

-----------  = 100     or     --------- = 1

     2                                2*(5+5)

 

As written, because the multiplication comes before the division, the correct problem and solution is:

 

    20
----------- = 1
2*(5+5)

 

If the (5+5) belonged in the numerator, the problem should be written as (20/2)(5+5).