 This is a mathematical snack from the Association of Teachers of Mathematics. Here is the domino. A domino has two sections. In one section it's got a one in it and in another section it has two in it. Here's another domino. This domino has three spots in one section and no spots in the other section. Here's another domino. Wait a minute. Oh, it's the 00 domino. It has no spots in either of the two sections. I am going to put down all the dominoes that live in the 33 set of dominoes. There are 10 of them. If I try to put that domino into the sets then it would not be allowed because this has got five spots in and the most number of spots in the 33 set of dominoes is going to be three. I'm going to remove that. Okay, two questions. The first question is how can I work out how many spots there are all together without counting every single spots? So instead of going one, two, three, four, five, six, seven, eight, nine, ten, eleven and so on, how might I find a way of working out the total number of spots without counting them one by one? The second problem is in the 33 sets there are one, two, three, four, five, six, seven, eight, nine, ten dominoes all together. How many dominoes would there be in a 44 set of dominoes? And how many spots would there be in a 44 set of dominoes? What about smaller sets of dominoes or larger sets of dominoes?