This will help you memorise the last digit of the 9 times table. Spread out all your fingers.
1x9 = 9 Hide 1 thumb, now you've got 9 fingers.
2x9 = 18 Hide another finger from the same hand, now you've got 8 fingers. To get the number of tens, you do this: 2 - 1. So the result of 2x9 = 18.
3x9 = 27 Hide another finger from the same hand, now you've got 7 fingers. To get the number of tens, you do this: 3 - 1. So the result of 3x9 = 27.
4x9 = 36 Hide another finger from the same hand, now you've got 6 fingers. To get the number of tens, you do this: 4 - 1. So the result of 4x9 = 36.
5x9 = 45 Hide another finger from the same hand, now you've got 5 fingers. To get the number of tens, you do this: 5 - 1. So the result of 5x9 = 45.
6x9 = 54 Hide another finger from the same hand, now you've got 4 fingers. To get the number of tens, you do this: 6 - 1. So the result of 6x9 = 54.
7x9 = 63 Hide another finger from the same hand, now you've got 3 fingers. To get the number of tens, you do this: 7 - 1. So the result of 7x9 = 63.
8x9 = 72 Hide another finger from the same hand, now you've got 2 fingers. To get the number of tens, you do this: 8 - 1. So the result of 8x9 = 72.
9x9 = 81 Hide another finger from the same hand, now you've got 1 finger. To get the number of tens, you do this: 9 - 1. So the result of 9x9 = 81.
10x9 = 90 For 10x9 you've got zero fingers left!