Think of a number between 1 and 31 that you would like to represent on one hand. Hold up the fingers which when their numbers are added to each other = the number you thought of. The fastest way to find the correct fingers is to start with the finger representing the largest number that fits into your number, if it is a still larger number then hold up the next largest number finger that will fit and so on until you can represent the number with those fingers. For example, to represent a 21 choose the little finger and the middle finger and the thumb, = 16 + 4 + 1, = 21. So if you hold up all five fingers and add the numbers represented they add up to 31, a large number to count on one hand. Indeed if you extend this system to both hands you can count up to 1023 on them. Notice that each number has twice the value of the previouse one.

The game goes like this. Write down the numbers 1 to 26 and under the numbers write the alphabet, i.e. 1=A 2=B - 26=Z. Now its possible to send messages from one to the other by representing the letters with numbers with your fingers by some fingers held up and the others kept down. You send a number/letter at a time and the other person sums the finger values & then writes them down and translates them into letters until they have a complete word. For example to send the letter "I" hold up the thumb and the third finger to represent 1+8=9=letter "I". It helps if the other person has a picture of a hand with these numbers written at the finger tips, either drawn or you could print out two copies of this photograph of a hand. An adult should start the game with a child & if there are two children who can play it with each other they could be left to play it together. My daughter could do this when she was four years old, so its not very difficult to play. An 11 year old I showed this to soon started to recognise the letter represented by the fingers held up without bothering with the numbers. I found that many children enjoy playing this. Its good practice at addition, also an introduction to the idea of a code and an introduction to the binary system which is used everywhere in computers.