Sure thing! We've got 623 and we're gonna multiply it by 13. That's the same as adding 623 to itself 13 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
Step 10: 5607 + 623 = 6230
Step 11: 6230 + 623 = 6853
Step 12: 6853 + 623 = 7476
Step 13: 7476 + 623 = 8099

So, 623*13 = 8099