Question

how can you tell if a number is divisible by 3

Answer 1

add up the numbers and if the sum is divisible by 3 the original number is also divisible by 3.

ex: 357÷3

3+5+7=15
15÷3=5

so 357 is divisible by 3.

Answer 2

If the sum of the numbers can be divisible by 3, Then the number itself must also be divisible by 3.
EX. Is 1,530 divisible by 3?
*Well lets see, 1+5+3+0=9  Since 9 is divisible by 3, we know that 1,530 is divisible by 3.*