A number is divisible by 3 if sum of its all digits is also divisible by 3.

Let us we will apply this interesting math rule on following examples.

Is 111 is divisible by 3?

Sum of digits is 3 which is divisible by 3, so the number 111 is divisible by 3.
(Do this step in your mind).

Is 168 is divisible by 3?

Sum of digits is 15 which is divisible by 3, so the number 168 is divisible by 3.
(Do this step in your mind).

Is 323 is divisible by 3?

Sum of digits is 8 which is not divisible by 3, so the number 323 is not divisible by 3.
(Do this step in your mind).

Is 12345 is divisible by 3?

Sum of digits is 15 which is divisible by 3, so the number 12345 is divisible by 3.
(Do this step in your mind).

Is 78453 is divisible by 3?

Sum of digits is 27 which is divisible by 3, so the number 78452 is divisible by 3.
(Do this step in your mind).

Is 98989698 is divisible by 3?

If you feel the result 66 is a large number or feel difficult to divide then you can apply the above rule again.

Now after apply the second time this rule the sum of digits is 12 which is divisible by 3, so the number 98989698 is divisible by 3.
(Do this step in your mind).

An Amazing math fact about divisible by 3?

Any 3-digit number with sequential digits, e.g., 123, 234, 456 and so on are always divisible by 3. This is another interesting fact.