Question

The four digit numeral 3AA1 is divisible by 9. What digit does A represent

Answer 1

A = 2, the number is 3221

Explanation:

In order for the number to be divisible by 9, the sum of it's digit has to be divisible by 9.

In our case,
`4+A+A+1= 9k` where k is an integer. the easiest way happens when k=1

`5+2A= 9 \rightarrow 2A=4 \rightarrow A = 2`

Higher values of k will likely most work (with k=2 you get A to be a non-integer, which can't work since it's the digit of a number, and with higher values of K you're not getting a number in base 10.