If 64y8 is exactly divisible by 3, then the least value of y is
We know that if sum of digits of a number is divisible by 3, then the number is divisible by 3.
Here,
6 + 4 + y + 8 = multiple of 3
18 + y = 0, 3, 6, 9, ….
Hence,
18 + y = 18
∴ y = 0
the least value of y is 0.