A multiplication table for the integers from 0 to 10 contains 121 entries. These entries correspond to the basic multiplication facts that need to be mastered in the elementary grades. To ease this task, the fundamental properties of multiplication can be used to reduce the number of facts that require actual memorization.
For example, because 6 × 7 = 42, there is no need to memorize 7 × 6 = 42, since the Commutative Property of Multiplication states that 6 × 7 = 7 × 6. Thus, mastering of the 66 shaded entries (on or below the diagonal) is the same as mastering all 121 entries