The most common hand is the multiple calculation of 9.

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 bent fingers. The left hand index is 6 and the right hand index is 3. Put them together and you can get the answer that 7×9 is 63.

Why do most of our students find mathematics boring and difficult to understand? Perhaps our teacher's teaching is too dull, or perhaps our students have not met a good teacher who is good at thinking, flexible, intuitive and rich in teaching. In fact, as long as we are good at thinking, mathematics itself is very interesting, so it can be said that it is a part of our daily life.