Num Properties - 4th ed Chp 10 (pg 129)

[anguyen]

Remainders and decimals - can someone pls elaborate on the very last paragraph of the page where it states:
7B = 20R
"otherwise, there is no way for a 7 to appear on the left side"

Why?

[Ben Ku]

This example simplifies to 7B = 20R, where B and R are both integers. Now if 20R = 7B, that means that 20R must be divisible by 7. 20 is not divisible by 7, so that means R must be divisible by 7 (or, R must be a multiple of 7).

Hope that helps.

[anguyen]

Got it, thx!

[Ben Ku]

no problem!