GM #coffeechain
To determine if a number is divisible by 3 check if the sum of its parts are divisible by 3.
For example, 7527
7+5+2+7=21
Since 21 is divisible by 3, that means 7527 is divisible by 3, specifically 7527=3*2509
Also, this can be repeated for 9. From 7527 we found the sum of the parts is 21 which is 2+1=3 which is divisible by 3. Since we can repeat this step a second time, this means 7527 is also divisible by 9.
#math