What to know just how perfect your butt is? I don't. But for those who are curious, there's an actual formula for grading the female derriere.

Developed by Dr. David Holmes, a psychology lecturer at Manchester Metropolitan University, and his team of British academics, this mathematical -- but also pretty subjective -- formula will tell you exactly how flawless your bum really is. It goes like this: (S+C) x (B+F) / (T-V). It's not as hard as it looks.

Translation: First, a woman must assess her assets on a scale of 1 to 20 (1 is worst; 20 is best) in the following categories.

S = overall shape (a ripe peach being just about right)
C = circularity (rounder is better)
B = bounciness (less wobble is preferred)
F = firmness (too much push to that cushion loses points)
T = skin texture (no cellulite, please)

Then she must calculate V, which is the ratio of her hips to waist. Then she simply does the math and determines how close she is to 80 -- a perfect score.

I'm not sure this little math problem does much for the scientific community. But it could be useful for comparison purposes if you're in the market for fine-tuning your physique. So if you need a little motivation -- perhaps you're a 60 and want to upgrade to a 70 -- this might do it for you.