Post Series: Fun with Maths

Having fun with maths is the best way to learn it! Let us teach you a simple trick.

## The five card magic

Preparation: Take five blank cards with numbers 1 to 5 written on them with black colour; one number on each card. On the back of the same cards, write numbers 6 to 10, with red colour taking care to write 6 on the back of 1; 7 at the back of 2 and so on.

The magic begins. Hand over all the five cards to a friend. Stand turning your back. Claim that you will do the magic without seeing.

Steps:

1. Ask the friend to drop all the five cards down on the ground.
2. Ask him/her for only one information – “How many red cards are facing up?”

Surprise your friend by telling the answer to the addition of all five numbers that are facing up.

Trick: The maths behind this magic is that the sum of 1 to 5 is 15. So, if no red card is up you’ll say the sum is 15. Each red card is exactly 5 more than the black number on the other side. So, if one red card is up, the answer is 15 + 5 = 20. If two red cards are up, the answer is 15 + 10 = 25 and so on. Have fun!!!