Introduction to Order of Operations

I can add 3 and 7 to make 10 then 5 to make 15. Or I can add 7 and 5 to make 12 then 3 to make 15. The order does not matter.

The order does matter. (3 + 2) x 4 = 5 x 4 = 20 and 3 + (2 x 4) = 3 + 8 = 11.

4 + 2 x 5

Sample answer: Scientists need to evaluate expressions to calculate important numbers. If two scientists do the same calculation, they need to get the same answer.

Sample answer: I multiply and divide first. If there is more than one multiplication or division I calculate left to right. Then I add or subtract, left to right.

(5 – 2) – 1 = 2 and 5 – (2 – 1) = 4. You do not get the same value. In the first example, you subtract 2 from 5 first and then subtract 1. In the second example, you subtract 1 from 2 and then you subtract that answer from 5. This results in different answers for the two expressions.

Add 6 + 2 to get 8. Subtract 3 from 8 to get 5. Multiply 5 x 8 to get 40.

(5 + 3) x (15 – 13)

6 6/8 or 6 3/4

65 – (15 + 30)