Let's get this math done. We have 623 and we're going to multiply it by 9. This is the same as taking 623 and adding it to itself 9 times.
Step 1: 0 + 623 = 623
Step 2: 623 + 623 = 1246
Step 3: 1246 + 623 = 1869
Step 4: 1869 + 623 = 2492
Step 5: 2492 + 623 = 3115
Step 6: 3115 + 623 = 3738
Step 7: 3738 + 623 = 4361
Step 8: 4361 + 623 = 4984
Step 9: 4984 + 623 = 5607

So, 623*9 = 5607