Answer :

diene
the pattern is:
multiply by 4, divide by 2, multiply by 4...etc
so what comes next is 16*4=64
Your answer is 64.
If you look at it the pattern is:
Multiply by 4, then divide by 2
4 times 4= 16
16 divided by 2= 8
8 times 4= 32
32 divided by 2= 16
Now you would multiply by 4
16 times 4= 64