Let's roll up our sleeves and solve this. We have 698 and we're going to multiply it by 31, essentially adding 698 to itself 31 times.
Step 1: 0 + 698 = 698
Step 2: 698 + 698 = 1396
Step 3: 1396 + 698 = 2094
Step 4: 2094 + 698 = 2792
Step 5: 2792 + 698 = 3490
Step 6: 3490 + 698 = 4188
Step 7: 4188 + 698 = 4886
Step 8: 4886 + 698 = 5584
Step 9: 5584 + 698 = 6282
Step 10: 6282 + 698 = 6980
Step 11: 6980 + 698 = 7678
Step 12: 7678 + 698 = 8376
Step 13: 8376 + 698 = 9074
Step 14: 9074 + 698 = 9772
Step 15: 9772 + 698 = 10470
Step 16: 10470 + 698 = 11168
Step 17: 11168 + 698 = 11866
Step 18: 11866 + 698 = 12564
Step 19: 12564 + 698 = 13262
Step 20: 13262 + 698 = 13960
Step 21: 13960 + 698 = 14658
Step 22: 14658 + 698 = 15356
Step 23: 15356 + 698 = 16054
Step 24: 16054 + 698 = 16752
Step 25: 16752 + 698 = 17450
Step 26: 17450 + 698 = 18148
Step 27: 18148 + 698 = 18846
Step 28: 18846 + 698 = 19544
Step 29: 19544 + 698 = 20242
Step 30: 20242 + 698 = 20940
Step 31: 20940 + 698 = 21638

So, 698*31 = 21638