The smallest number that is divisible by 32, 64, 128 is the LCM of 32, 64, 128.
LCM of 32, 64, 128 =
= 2×2×2×2×2×2×2
=128
When 128 is divided by 32, 64 & 128 there is no remainder. So, to get remainder 8 when divided by 32, 64 & 128, 8 is to be added to 128 i.e., 128+8 = 136