Divisibility by 9 Test:

A number is divisible by 9 if the
sum of the digits is divisible by
9.

This one's really going to help you remember your "nines" times tables!


Let's do one:

Does 9 go into 487,521?  ( Is 487,521 divisible by 9? )
 

1 )  Add up the digits...  4 + 8 + 7 + 5 + 2 + 1 = 27


2 )  Does 9 go into 27?  Yep!


So, 487,521 is divisible by 9.

 

Here's another one:

Does 9 go into 922?  ( Is 922 divisible by 9? )


9 + 2 + 2 = 13


9 doesn't go into 13.  So, 922 is not divisible by 9.