Staff Review
This lesson explains a very useful tactic that many kids learn in elementary school, how to multiply by 9 with your fingers. Also, different methods of multiplying by 9 are shown that do not involve using your fingers. One pattern that is pointed out is that the product of 9 times a single digit number gives a first digit of one less than the number you are multiplying by and a second digit that is 9 minus the first digit. Also, multiplying 9 by a multi-digit number where all digits are the same is explained.