 a mathematical snack from the Association of Teachers of Mathematics. We have four numbers, one, two, three and four, and the task is to see what other numbers you can make. There are two rules, one is you must generally use these numbers and the other is you must use them all. So I'll look at that and I might start by writing 14. 14, that's used the one and the four. Two threes are six, so I might want to do 14 plus two times three. 14 and six is 20. So I have made 20, but if you take the calculator on your phone or some other calculator and try and put this in you might get 14 plus two is 16 times three and it will suddenly say 48. So to get this right I need to put a bracket around the two and the three. 14 plus two times three is certainly 20. I could write 14 subtract two subtract three and that is 14 subtract two is 12, subtract three is nine. So each time I've used a one, a two, a three and a four, but I can do other things. I could write four plus three and put it in a bracket. Little two up there, that means squared. Four and three is seven. Seven squared, what haven't I used? I haven't used the one plus one. Seven squared is 49, seven sevens plus one is 50. So I have got 50. The challenge is can you make all the numbers from one to 50 each time using one, two, three and four?