How do you figure out 15 times 8 mentally?

Answer 1

There are many ways, so you can choose the one that's easier for you.

Example 1:

15 X 8 can be broken down into:

15 X 4 X 2

therefore 15 X 4 = 60

therefore 60 X 2 = 120

Example 2:

15 X 8 can be broken down into:

(10 X 8) + (5 X 8)

^ Brackets have been inserted for clarification, though they are not required.

therefore 10 X 8 = 80

and 5 X 8 = 40

therefore 80 + 40 = 120

Example 3:

15 X 8 can be re-written as:

(15 X 10) - (15 X 2)

^ Brackets have been inserted for clarification, though they are not required.

therefore 15 X 10 = 150

and 15 X 2 = 30

therefore 150 - 30 = 120