28 ÷ 7 x 6

Question

This question is in our third grade math book.  If you use order of operations, the problem is impossible for a third grader to answer.  Don't you have to do multiplication, then division.  The answer key says to do 28 ÷7 = 4, then 4 x 6 = 24.  Can you do that?  I thought it was x, ÷, + then -.

Answer 1

Hi Stacey, the order of operation is sometimes confused because of certain mnemonics that exist. Multiplication and division have the same ranking. The same is true for addition and subtraction. The rule for multiplication and division or addition and subtraction, is first come, first served.

 

In this example, division comes before the multiplication, therefore, do the division first.

 

28 ÷ 7 = 4

 

Next, do the multiplication:

 

4 X 6 = 24.

 

Questions?

Answer 2

Without any parentheses, you should work on this from left to right. The book's answer key is correct. You do the division first, then the multiplication.

 

Using PEMDAS, you remember that the order of operations is:

 

Parentheses first, then

Exponents, then

Multiplication and Division in order from left to right, then

Addition and Subtraction in order from left to right.

 

This is the proper way to use the order of operations without parentheses. Parentheses (of course) cause the rules to be applied differently.

 

Answer 3

The order of operations can be remembered by P-E-M-D-A-S (Please Excuse My Dear Aunt Sally).

 

This means (in order):

    Parentheses

    Exponentiation

    Multiplication and Division (left to right)

    Addition and Subtraction (left to right)

 

Thus:

  28 ÷ 7 x 6

      4 x 6

       24