Typographical number theory is a kind of mathematics that deals with the patterns that happen when you look at numbers. It looks at how adding some numbers together or writing them in different ways can show special patterns. For example, if you add the numbers from 1 to 6, the answer is 21. That's a special pattern because if you write the numbers like this: 1+2+3+4+5+6, you can make a triangle with the numbers, which makes it a special pattern.