I use to think of it like 10 and then subtract with the other factor. For example if you have 9x7, think 10x7 and then subtract 7. 70-7 = 63. And if you have 9

I use to think of it like 10 and then subtract with the other factor. For example if you have 9x7, think 10x7 and then subtract 7. 70-7 = 63. And if you have 9x9 just think 90-9=81. 9x10 = 100-10 = 90 9x15 = 150-15 = 135 and so on..