Let's get this math done. We have 641 and we're going to multiply it by 23. This is the same as taking 641 and adding it to itself 23 times.
Step 1: 0 + 641 = 641
Step 2: 641 + 641 = 1282
Step 3: 1282 + 641 = 1923
Step 4: 1923 + 641 = 2564
Step 5: 2564 + 641 = 3205
Step 6: 3205 + 641 = 3846
Step 7: 3846 + 641 = 4487
Step 8: 4487 + 641 = 5128
Step 9: 5128 + 641 = 5769
Step 10: 5769 + 641 = 6410
Step 11: 6410 + 641 = 7051
Step 12: 7051 + 641 = 7692
Step 13: 7692 + 641 = 8333
Step 14: 8333 + 641 = 8974
Step 15: 8974 + 641 = 9615
Step 16: 9615 + 641 = 10256
Step 17: 10256 + 641 = 10897
Step 18: 10897 + 641 = 11538
Step 19: 11538 + 641 = 12179
Step 20: 12179 + 641 = 12820
Step 21: 12820 + 641 = 13461
Step 22: 13461 + 641 = 14102
Step 23: 14102 + 641 = 14743

So, 641*23 = 14743