The document presents a mathematical trick for multiplying numbers with repeated ones. [1] It shows examples of multiplying numbers with increasing numbers of repeated ones, like 11 x 11 = 121 and 111 x 111 = 12321. [2] The trick is to write the first few natural numbers, drop the last, then write them in reverse order and combine them. [3] For example, to do 11 x 11, write 12 and then 1, giving 121.