Do you call heads or tails in a coin flip? According to a recent study tails may not be the best call.

A math professor at Stanford University has figured out that the odds of heads or tails coming up in a coin flip is not 50-50.

He found that whichever side is facing up when the coin is flipped is slighty more likely to come up. So if you flip a coin with the heads side up, there's a 51% chance it will land on heads and a 49% chance it will land on tails.

Here is his explanation. Think about when you count numbers, starting from one. No matter where you stop, you'll either have more odd numbers or the same number of odd and even numbers. You'll never have more even than odd.

It's the same principle with flipping a coin. If you start on heads and flip it, heads will always have the advantage. Tails can pull even, but never pass heads.

So it won't give you a giant advantage in coin flips, but it will give you a small advantage. And over the course of a lot of coin flips in your life, it probably will help your odds of winning.