OK, let's work through this together. We're starting with 9 and we're going to multiply it by 9, which means we add 9 to itself 9 times.
Step 1: 0 + 9 = 9
Step 2: 9 + 9 = 18
Step 3: 18 + 9 = 27
Step 4: 27 + 9 = 36
Step 5: 36 + 9 = 45
Step 6: 45 + 9 = 54
Step 7: 54 + 9 = 63
Step 8: 63 + 9 = 72
Step 9: 72 + 9 = 81

So, 9*9 = 81