how Xi works: it adds the 2 digets together so like 5 + 5 is ten then it will repet multipying the first diget and the second diget first + second diget times so 5 + 5 = 250. 10 + 10 = 2000. the math thing's name is Xi this is what it should look like while using: Xi(5, 5) = 250, Xi(10, 10) = 2000