If you add the individual numbers of a number together, you may be able to see if you can divide by 3. This is confusing, so let me explain.
141
1+4+1=6
6 is divisible by 3; therefore 141 is divisible by 3
141/3=47
21
2+1=3
21/3=7
2361
2+3+6+1=12
2361/3=787
