Our bodies are really great. The hand is an ordinary calculator. The most common hand is the multiple calculation of 9. Parents may not understand, but many children will soon learn. When calculating the multiple of 9, put your hands on your knees and count your fingers from left to right, as shown in the table below.

Now choose the multiple of 9 you want to calculate, assuming that the multiplication is 7×9. As shown in the above picture, just bend the finger marked with the number 7. Then count the left index finger of the bent finger as 6, and the index of the left hand on its right is 3. Put them together, the answer of 7×9 is 63.