Question

If a number 3A98 is divisible by 11, find the value of A.
(3 marks)

Answer 1

Solution:

To check the divisibility of a number by 11, the rule is to find the difference between the sum of the digits at odd places (from the right) and the sum of the digits at even places (from the right) of the number. If the difference is either 0 or divisible by 11, then the number is divisible by 11.
(1 mark)

3 + 9 = 12, A + 8

A + 8 - 12 = 0
A - 4 = 0 or A - 4 = 11

A = 4 or A = 15, A = 15 is not possible, as it is a single digit.
(1 mark)

So, the number is 3498.
(1 mark)