This page continues with our series on tests of divisibility.
To find out whether a number is exactly divisible by 3:
Add up the digits of the number.
If the total is divisible by 3 then so is the number.
Eg: 345
3 + 4+ 5 = 12.
12 is divisible by 3 so 345 is also divisible by 3.
To find out if a number is exactly divisible by 6:
Check that it is even.
If it is even, apply the test of divisibility for 3. If the total of the digits is divisible by 3 and the number is even, it is also divisible by 6.
Eg 348
348 is even.
3 + 4+ 8 = 15.
15 is divisible by 3 so 348 is divisible by 6.