Multiply up to 20 x 20 in your Head
Picture the two numbers in your head, the larger above the smaller. For example, let’s use 16×18. Imagine 18 above 16 in your head. Kill the 1 on the bottom number (the 1 on the 16). If you are following this example, you will now have 18 above 6. Add the two numbers. You should Read More …