Question

Using divisibility tests, determine which of the following numbers are divisible by 11.
(a) 10824 (b) 7138965 (c) 70169308

Answer 1

Rule: Add and subtract digits in an alternating pattern Then the answer must be divisible by 11.
10824 = 1 - 0 + 8 - 2 + 4 = 13 - 2 = 11  .....Yes, it is divisible by 11.

7138965 = 7 - 1 + 3 - 8 + 9 - 6 + 5 = 24 - 15 = 9
                                           .....No, it is not  divisible by 11.

70169308 = 7 - 0 + 1 - 6 + 9 - 3 + 0 - 8 = 17 - 17 = 0   .....Yes, it is divisible by 11.