Today I learnt...

How to use a binary code. A binary code can have about 4 columns. 1 with 8 squares, one with 4, one with 2 and one with 1. If you want to show 12 in binary, you need to have, e.g 12 pennies. You need to use them one each column but there is a catch, you can only have full or empty columns, no half-filled. You can use the columns with 8 and 4 squares because they add up to 12. There can only be 1 solution. So in binary, 12 is on,on,off,off.