Sure thing, let's get straight to it. We start with 421 and we're going to multiply it by 31, which means adding 421 to itself 31 times.
Step 1: 0 + 421 = 421
Step 2: 421 + 421 = 842
Step 3: 842 + 421 = 1263
Step 4: 1263 + 421 = 1684
Step 5: 1684 + 421 = 2105
Step 6: 2105 + 421 = 2526
Step 7: 2526 + 421 = 2947
Step 8: 2947 + 421 = 3368
Step 9: 3368 + 421 = 3789
Step 10: 3789 + 421 = 4210
Step 11: 4210 + 421 = 4631
Step 12: 4631 + 421 = 5052
Step 13: 5052 + 421 = 5473
Step 14: 5473 + 421 = 5894
Step 15: 5894 + 421 = 6315
Step 16: 6315 + 421 = 6736
Step 17: 6736 + 421 = 7157
Step 18: 7157 + 421 = 7578
Step 19: 7578 + 421 = 7999
Step 20: 7999 + 421 = 8420
Step 21: 8420 + 421 = 8841
Step 22: 8841 + 421 = 9262
Step 23: 9262 + 421 = 9683
Step 24: 9683 + 421 = 10104
Step 25: 10104 + 421 = 10525
Step 26: 10525 + 421 = 10946
Step 27: 10946 + 421 = 11367
Step 28: 11367 + 421 = 11788
Step 29: 11788 + 421 = 12209
Step 30: 12209 + 421 = 12630
Step 31: 12630 + 421 = 13051

So, 421*31 = 13051