Question

Find the least value that must be given to ‘a’, so that the number 91876a2 is divisible by 8?

Answer 1

Hey buddy! Here's your answer!

For divisibility by 8, we need to check if the last 3 numbers are divisible by 8.

6a2 should be divisible by 8. So starting from 0 to 9, we replace a by these digits, till we get 6a2 ≅ 0 mod 8.

x ≅ y mod b is just a way of writing that when x is divided by b the remainder is y. This often comes handy during divisibility. When remainder is 0, it means the number is divisible.

a) 602 ≅ 2 mod 8  -----> Not possible

b) 612 ≅ 4 mod 8 --------> Not possible

c) 622 ≅ 6 mod 8 ----------> Not possible

d) 632 ≅ 0 mod 8 ----------> Possible

So a = 3. As we need the least value the correct answer is 3.

Hope this helps! :)