Divisibility by 11

If

So, if the difference is 0, 11, 22, 33, ….

Then, Number is divisible by 11

Is 308 divisible by 11?

Sum of digits at odd Places = 8 + 3 = 11

Sum of digits at even Places = 0

Difference = 11 − 0 = 11

Since 11 is divisible by 11

∴ 308 is divisible by 11

Is 1331 divisible by 11?

Sum of digits at odd Places = 1 + 3 = 4

Sum of digits at even Places = 3 + 1 = 4

Difference = 4 − 4 = 0

Since difference is 0

∴ 1331 is divisible by 11

Is 61809 divisible by 11?

Sum of digits at odd Places = 9 + 8 + 6 = 23

Sum of digits at even Places = 0 + 1 = 1

Difference = 23 − 1 = 22

Since 22 is divisible by 11

∴ 61809 is divisible by 11

Is 5081 divisible by 11?

Sum of digits at odd Places = 1 + 0 = 1

Sum of digits at even Places = 8 + 5 = 13

Difference = 13 − 1 = 12

Since 12 is not divisible by 11

∴ 5081 is not divisible by 11