This math is about finding a pattern. There is a basic rule and a general rule. To find a basic rule you must find what the pattern is adding by. To find a general rule, you have to find the difference between the top table numbers and the bottom table. 1 and 3 have something, 1 needs to be multiplied by 2 and add 1. The rule is 2n+1. It works for the other numbers which helps me find the answer for bigger numbers.