Have someone hide a dime in one hand and a penny in the other.
Tell them that you will guess which hand has the dime in it after they do a simple calculation.
Have them multiply the amount of money in their right hand by 5.
Have them multiply the amount of money in their left hand by 6.
Have them add the two amounts together and tell you the sum.
If the sum is an odd number, the dime is in the left hand.
If the sum is an even number, the dime is in the right hand.