Find all possible values of y for which the 4-digit number 64y3 is divisible by 9.
Question:

Find all possible values of y for which the 4-digit number 64y3 is divisible by 9. Also, find the numbers.

Solution:

For a number to be divisible by 9, the sum of the digits must also be divisible by 9.

$6+4+y+3=13+y$

For this to be divisible by 9 :

$y=5$

The number will be 6453 .