Take 5 coins and have one person arrange them the way they want (face or crown up). For example:
Note that in this example 3 crowns and 2 heads were chosen. Now turn around and ask the person to flip as many coins as he wants. Each time she turns a coin, she must say the word "I will come".
When you are finished, ask the person to place their hand on one of the coins. Now you will turn around again and tell if the coin under the person's hand is FACE or CROWN! Want to know how?
The trick: Before turning on your back, count the number of crowns. In the example are 3, ie it is an odd number. Each time the person says the word "I will come," the number of crowns changes from odd to even or from odd to even. For example, in the above situation, if the person says "I will come" three times, we will have:
1st time - no. of crowns
2nd time - No. of odd crowns
3rd time - no. of crowns
Turning your head around will have your hand on one of the coins, but you will be seeing the other four. So in our example, just see if the number of crowns you are seeing is even. If not, the coin under your hand is CROWN. Otherwise, it's FACE.
Let's illustrate our example so that you understand better. Imagine that from the coins in the drawing above we turn the first and second. Then we would have:
As 2 coins were turned, the number of crowns should remain odd. For example, if the person lays a hand on the fourth coin:
You will know that the missing coin is FACE, as there is already an odd number (1) of crowns.