[phantom4570]

You are given eight coins and told that one of them is counterfeit.
The counterfeit coin is slightly heavier than the other seven. Otherwise, the coins look identical.
Using a simple balance scale, how can you determine which coin is counterfeit using the scale only twice?

I'll post the answer after you guys ponder it for awhile.

 

[bearcat6]

Lets see, put three on each side, leaving off two, if the heavy one is on one side put two of those on the scale, if one those balance the one you left off is the heavy one, if the first six balance the heavy one is one of the two left off so you weigh them against each other.

 

[phantom4570]

We have a winner.