Question

Test the divisibility of the following numbers by 11.
(a) 5335
(b) 9020814

Answer 1

We know that a number is divisible by 11, if the difference of sum of digits at even and odd places from the right is divisible by 11.
(a) We have, 5335
Sum of digits at even places from the right = 3 + 5 = 8
Sum of digits at odd places from the right = 5 + 3 = 8
So, difference = 8 - 8 = 0 (divisible by 11)
Hence, it is divisible by 11.
(b) We have, 9020814
Sum of digits at even places from the right = 1 + 0 + 0 = 1
Sum of digits at odd places from the right = 4 + 8 + 2 + 9 = 23
So, difference = 23 - 1 = 22 (divisible by 11)
Hence, it is divisible by 11.