According to euclid`s algorithm
a=bq+r
Let a=16 (4^2) and b=6
then 16=6*2+4
Let a=64 (4^3) and b=6
then 64=6*10+4
Let a=256 (4^4) and b=6
then 256=6*42+4
If we continue in this manner, we find that the remainder for any power of 4 when divided by 6 will be 4 only.
Hence the remainder for 4^96 when divided by 6 will be 4.