OK, let's crack this. We're given 793 and our task is to multiply it by 27. Essentially, we'll be adding 793 to itself 27 times.
Step 1: 0 + 793 = 793
Step 2: 793 + 793 = 1586
Step 3: 1586 + 793 = 2379
Step 4: 2379 + 793 = 3172
Step 5: 3172 + 793 = 3965
Step 6: 3965 + 793 = 4758
Step 7: 4758 + 793 = 5551
Step 8: 5551 + 793 = 6344
Step 9: 6344 + 793 = 7137
Step 10: 7137 + 793 = 7930
Step 11: 7930 + 793 = 8723
Step 12: 8723 + 793 = 9516
Step 13: 9516 + 793 = 10309
Step 14: 10309 + 793 = 11102
Step 15: 11102 + 793 = 11895
Step 16: 11895 + 793 = 12688
Step 17: 12688 + 793 = 13481
Step 18: 13481 + 793 = 14274
Step 19: 14274 + 793 = 15067
Step 20: 15067 + 793 = 15860
Step 21: 15860 + 793 = 16653
Step 22: 16653 + 793 = 17446
Step 23: 17446 + 793 = 18239
Step 24: 18239 + 793 = 19032
Step 25: 19032 + 793 = 19825
Step 26: 19825 + 793 = 20618
Step 27: 20618 + 793 = 21411

So, 793*27 = 21411