Explanation Divisibility Test for 4:
If the last 2 digits of a number is divisible by 4 then the number is divisible by 4. This comes straight from the fact that 100 is divisible by 4, and hence the cycle repeats just like from 0.
Now looking at the number 178564 , 64 is the number formed by the last 2 digit which is divisible by 4.