Let's roll up our sleeves and solve this. We have 703 and we're going to multiply it by 21, essentially adding 703 to itself 21 times.
Step 1: 0 + 703 = 703
Step 2: 703 + 703 = 1406
Step 3: 1406 + 703 = 2109
Step 4: 2109 + 703 = 2812
Step 5: 2812 + 703 = 3515
Step 6: 3515 + 703 = 4218
Step 7: 4218 + 703 = 4921
Step 8: 4921 + 703 = 5624
Step 9: 5624 + 703 = 6327
Step 10: 6327 + 703 = 7030
Step 11: 7030 + 703 = 7733
Step 12: 7733 + 703 = 8436
Step 13: 8436 + 703 = 9139
Step 14: 9139 + 703 = 9842
Step 15: 9842 + 703 = 10545
Step 16: 10545 + 703 = 11248
Step 17: 11248 + 703 = 11951
Step 18: 11951 + 703 = 12654
Step 19: 12654 + 703 = 13357
Step 20: 13357 + 703 = 14060
Step 21: 14060 + 703 = 14763

So, 703*21 = 14763