How to find % body weight eaten

How do you find % of body weight eaten, divid snakes weight by prey weight or prey weight by snakes weight, its really confusing me, but i know its really simple

Prey weight / Snake weight x 100

Thats, so i fed my bp tonight, the mouse weighted about 25 grams, and my bp is 450 grams, so the % body weight eaten would be 5.5% is that good or should it be higher??

I don't go by % body weight eaten.

I try to make sure the rodents leaves a slight lump. Could you notice there was a mouse in there? What size mouse was it. I feed my 120g '08 adult mice...