Without delay, let's solve this. We've got 713 and we will be multiplying it by 21, that is, adding 713 to itself 21 times.
Step 1: 0 + 713 = 713
Step 2: 713 + 713 = 1426
Step 3: 1426 + 713 = 2139
Step 4: 2139 + 713 = 2852
Step 5: 2852 + 713 = 3565
Step 6: 3565 + 713 = 4278
Step 7: 4278 + 713 = 4991
Step 8: 4991 + 713 = 5704
Step 9: 5704 + 713 = 6417
Step 10: 6417 + 713 = 7130
Step 11: 7130 + 713 = 7843
Step 12: 7843 + 713 = 8556
Step 13: 8556 + 713 = 9269
Step 14: 9269 + 713 = 9982
Step 15: 9982 + 713 = 10695
Step 16: 10695 + 713 = 11408
Step 17: 11408 + 713 = 12121
Step 18: 12121 + 713 = 12834
Step 19: 12834 + 713 = 13547
Step 20: 13547 + 713 = 14260
Step 21: 14260 + 713 = 14973

So, 713*21 = 14973