Question

Explain 2 ways to evaluate 15(90-3)

Answer 1

Distribute the 15 first or subtract inside the parentheses first and then multiply

Answer 2

First Way:

15(90-3)

=15(10*9-3)

=15*10*9-15*3

=150*9-45

=1,350-45

=1,305

-----------------

Second Way:

15(90-3)

=15(87)

=15(80+7)

=15(10*8+7)

=15*10*8+15*7

=150*8+(10+5)*7

=1,200+70+35

=1,200+105

=1,305