Always bet tails*. The odds of a toss coming up tails is approximately 2:1. This is because the head side weighs more, so it will land down more often than not. I love being a physics dork!

_{* This is at least the case on older quarters. Some of the state-specific quarters have a different balance.} WHAT?

The probability of getting heads or tails is roughly 50/50 regardless of old or new quarters. State quarter, Standing Liberties, per 1963 silver, copper clap or worn.

Now to be 100% fair there is an extremely SLIGHT chance that one side will prevail over the other and that is purely based on which side was facing up when the coin was flipped.

So according to mathematicians from Stanford University and the University of California, Santa Cruz. For a coin toss to be truly random, they say, you have to flip the coin into the air so that it spins in just the right way.

Most of the time, though, the coin doesn't spin perfectly. It might tip and wobble in the air. Sometimes it doesn't even flip over.

In experiments, the researchers found that it's practically impossible to tell from watching a tossed coin whether it has flipped over. A tossed coin is typically in the air for just half a second, and a wobble can fool the eyes, no matter how carefully you watch.

To see how wobbling affects the outcome, the researchers videotaped actual coin tosses and measured the angle of the coin in the air. They found that a coin has a 51 percent chance of landing on the side it started from. So, if heads is up to start with, there's a slightly bigger chance that a coin will land heads rather than tails.

When it comes down to it, the odds aren't very different from 50-50. In fact, it would take about 10,000 tosses for you to really notice the difference.

So heads I win, tails you lose.

http://www.sciencenews.org/articles/20040228/fob2.asp