8 X 45 by using the distributive property?

Question

Go Math - Common Core is asking a question for the students to mentally find 8 X 45 by using the Distributive Property 

Answer 1

8*45=8*(40+5)=8*40+8*5=320+40=360

 

I did it in my head this way. ;-)

Answer 2

Hi Phyllis -- you may like eight 50's (400) with a 10% "discount" (-40) ==> 360 ... 8x44 would be eight 40's (320) plus a 10% "tip" (+32) = 352 ... 8x42 would be eight 40's with a "5% tip" ... 320 +16 =336 ... Best regards :)

Answer 3

I am doing it in my head this way:

(10 - 2) * 45 = 10*45 - 2*45 = 450 - 90 = 360

:-)