This document contains 3 identities related to multiplication and addition of numbers: 1) To multiply the sum of two numbers by a third number, we multiply each number in the sum separately and add the results, following the identity (x+y)z = xz + yz. 2) To multiply the sum of two numbers by the sum of two other numbers, we multiply each number in the first sum by each number in the second sum and add the results, as expressed by the identity (x+y)(u+v) = xu + xv + yu + yv. 3) The document presents the identities (x-y)2 = x2 - 2xy +