OK, let's crack this. We're given 907 and our task is to multiply it by 9. Essentially, we'll be adding 907 to itself 9 times.
Step 1: 0 + 907 = 907
Step 2: 907 + 907 = 1814
Step 3: 1814 + 907 = 2721
Step 4: 2721 + 907 = 3628
Step 5: 3628 + 907 = 4535
Step 6: 4535 + 907 = 5442
Step 7: 5442 + 907 = 6349
Step 8: 6349 + 907 = 7256
Step 9: 7256 + 907 = 8163

So, 907*9 = 8163