A Maths Magic Trick

Step 1: You will need

a deck of cards a willing participant a calculator the universal truth of maths

1. Step 2: The trick

   Tell the participant that you're going to think of a card, the identity of which will be revealed later. Deal one card onto the table face down. Now give the deck to your participant. Tell them to think of a number card in their head as they look through the deck. Tell them not choose a picture card such as a king or an ace. Tell them to find this card in the deck and place it face down on the table next to the other face down card. Now hand them the calculator. This is where the maths comes in. Ask them to double the number of the card they chose. then to add 2, multiply by 5, and finally subtract 7 from the answer. Now ask them to reveal their answer. In this case it's 23. Now ask your participant to turn over the card they selected. It's the first digit of their answer. Now turn over your prediction card, it's the second digit of their answer. Magic? or .... maths?

2. Step 3: Maths

   The secret to this trick, is maths. The magician knows that with this special sum, whatever number the participant chooses, the answer will always end with a three. Knowing this secret, the magician need only select a three as his prediction card, place this face down on the table and the trick will always be a success. Apply the correct equation, and the result is guaranteed every time.