16
400
25
16
16 divided by 0.04 = 400
16
1.3125
25
Well, 4 divided by 16 is 1/4, so 16 into 400 billion it must be 100 billion times that. That makes it 25 billion. Or if you like, 400 divided by 16 is 25, leading to the same answer.
16 = 400/25
0.05
0.0143