Sure thing! We've got 689 and we're gonna multiply it by 21. That's the same as adding 689 to itself 21 times.
Step 1: 0 + 689 = 689
Step 2: 689 + 689 = 1378
Step 3: 1378 + 689 = 2067
Step 4: 2067 + 689 = 2756
Step 5: 2756 + 689 = 3445
Step 6: 3445 + 689 = 4134
Step 7: 4134 + 689 = 4823
Step 8: 4823 + 689 = 5512
Step 9: 5512 + 689 = 6201
Step 10: 6201 + 689 = 6890
Step 11: 6890 + 689 = 7579
Step 12: 7579 + 689 = 8268
Step 13: 8268 + 689 = 8957
Step 14: 8957 + 689 = 9646
Step 15: 9646 + 689 = 10335
Step 16: 10335 + 689 = 11024
Step 17: 11024 + 689 = 11713
Step 18: 11713 + 689 = 12402
Step 19: 12402 + 689 = 13091
Step 20: 13091 + 689 = 13780
Step 21: 13780 + 689 = 14469

So, 689*21 = 14469