OK, let's work through this together. We're starting with 921 and we're going to multiply it by 9, which means we add 921 to itself 9 times.
Step 1: 0 + 921 = 921
Step 2: 921 + 921 = 1842
Step 3: 1842 + 921 = 2763
Step 4: 2763 + 921 = 3684
Step 5: 3684 + 921 = 4605
Step 6: 4605 + 921 = 5526
Step 7: 5526 + 921 = 6447
Step 8: 6447 + 921 = 7368
Step 9: 7368 + 921 = 8289

So, 921*9 = 8289