I want to review the order of operations. It's simple, yet many people fail to follow the order and get the wrong answer.

The order of operations is as follows:

Parentheses
Exponents
Multiplication
Division
Addition
Subtraction

We can remember this by thinking of PEMDAS or by the sentence, "Please Excuse My Dear Aunt Sally"

For the following problem, suppose we solve this WITHOUT following the order of operations.

3 X (6 + 2) - 4 / 2 + 15 X 5 / 3 + 5^2

Without following the order of operations we would just solve from left to right

3 X 6 = 18

18 + 2 = 20

20 - 4 = 16

16 /2 = 8

8 + 15 = 23

23 X 5 = 125

125 / 3 = 41 2/3

41 2/3 + 5 = 46 2/3

(46 2/3)^2 = 2,177 7/9

Solving using the order of operations we get an entirely different, correct answer

3 X 8 - 4/2 + 15 X 5 /3 + 5^2

3 X 8 - 4/2 + 15 X 5/3 + 25

24 - 4/2 + 75/3 + 25

24 - 2 + 25 + 25

72