The fact family for 81 and 9 have only two number sentences because you can do only two things with the number 81 and 9. The number 81 is divided by 9 and we get the answer 9. and if you multiply the number 9 with 9, you will get the answer 81.
9 time 9 = 9 x 9 = 81 and, 81 / 9 = 9.