Question

Check the divisibility of the following numbers by $11$:

$61809$

Answer 1

A number is divisible by $11$, if the difference between the sums of alternate digits is either $0$ or a multiple of $11$.

Considering the number $61809$

Difference of sum of alternate digits is $(6+8+9)-(1+0)=23-1=22$, which is multiple of$11$

Hence, $61809$ is divisible by $11$