You will require one penny and one dime for this activity.
Ask someone to put a penny in one hand and a dime in the other.
The person must be able to do simple adding and multiplying in their head.
This trick will enable you to determine which coin is in which hand.
Tell the person to multiply what is in their right hand by 4, 6, or 8.
Then, tell them to multiply what is in their left hand by 3, 5, or 7.
Finally, ask them to add those two answers together and to give you the total.
If the total is even, then the penny is in their right hand.
If the total is odd, then the penny is in their left hand.
For Example :
Assume they put the penny in their right hand, and the dime in their left hand.
Now, if they choose to multiply the penny by 4, the result is 4.
And, if they choose to multiply the dime by 3, the result is 30.
The total 4 + 30 = 34, is even, therefore, the penny must be in their right hand.