Alright, let's solve this math problem step by step. First, we have the number 631. Next, we see the multiplication sign, which means we need to multiply something. And what are we multiplying it by? We multiply it by 129. So, we're going to take the number 631 and add it to itself 129 times.
Step 1: 0 + 631 = 631
Step 2: 631 + 631 = 1262
Step 3: 1262 + 631 = 1893
Step 4: 1893 + 631 = 2524
Step 5: 2524 + 631 = 3155
Step 6: 3155 + 631 = 3786
Step 7: 3786 + 631 = 4417
Step 8: 4417 + 631 = 5048
Step 9: 5048 + 631 = 5679
Step 10: 5679 + 631 = 6310
Step 11: 6310 + 631 = 6941
Step 12: 6941 + 631 = 7572
Step 13: 7572 + 631 = 8203
Step 14: 8203 + 631 = 8834
Step 15: 8834 + 631 = 9465
Step 16: 9465 + 631 = 10096
Step 17: 10096 + 631 = 10727
Step 18: 10727 + 631 = 11358
Step 19: 11358 + 631 = 11989
Step 20: 11989 + 631 = 12620
Step 21: 12620 + 631 = 13251
Step 22: 13251 + 631 = 13882
Step 23: 13882 + 631 = 14513
Step 24: 14513 + 631 = 15144
Step 25: 15144 + 631 = 15775
Step 26: 15775 + 631 = 16406
Step 27: 16406 + 631 = 17037
Step 28: 17037 + 631 = 17668
Step 29: 17668 + 631 = 18299
Step 30: 18299 + 631 = 18930
Step 31: 18930 + 631 = 19561
Step 32: 19561 + 631 = 20192
Step 33: 20192 + 631 = 20823
Step 34: 20823 + 631 = 21454
Step 35: 21454 + 631 = 22085
Step 36: 22085 + 631 = 22716
Step 37: 22716 + 631 = 23347
Step 38: 23347 + 631 = 23978
Step 39: 23978 + 631 = 24609
Step 40: 24609 + 631 = 25240
Step 41: 25240 + 631 = 25871
Step 42: 25871 + 631 = 26502
Step 43: 26502 + 631 = 27133
Step 44: 27133 + 631 = 27764
Step 45: 27764 + 631 = 28395
Step 46: 28395 + 631 = 29026
Step 47: 29026 + 631 = 29657
Step 48: 29657 + 631 = 30288
Step 49: 30288 + 631 = 30919
Step 50: 30919 + 631 = 31550
Step 51: 31550 + 631 = 32181
Step 52: 32181 + 631 = 32812
Step 53: 32812 + 631 = 33443
Step 54: 33443 + 631 = 34074
Step 55: 34074 + 631 = 34705
Step 56: 34705 + 631 = 35336
Step 57: 35336 + 631 = 35967
Step 58: 35967 + 631 = 36598
Step 59: 36598 + 631 = 37229
Step 60: 37229 + 631 = 37860
Step 61: 37860 + 631 = 38491
Step 62: 38491 + 631 = 39122
Step 63: 39122 + 631 = 39753
Step 64: 39753 + 631 = 40384
Step 65: 40384 + 631 = 41015
Step 66: 41015 + 631 = 41646
Step 67: 41646 + 631 = 42277
Step 68: 42277 + 631 = 42908
Step 69: 42908 + 631 = 43539
Step 70: 43539 + 631 = 44170
Step 71: 44170 + 631 = 44801
Step 72: 44801 + 631 = 45432
Step 73: 45432 + 631 = 46063
Step 74: 46063 + 631 = 46694
Step 75: 46694 + 631 = 47325
Step 76: 47325 + 631 = 47956
Step 77: 47956 + 631 = 48587
Step 78: 48587 + 631 = 49218
Step 79: 49218 + 631 = 49849
Step 80: 49849 + 631 = 50480
Step 81: 50480 + 631 = 51111
Step 82: 51111 + 631 = 51742
Step 83: 51742 + 631 = 52373
Step 84: 52373 + 631 = 53004
Step 85: 53004 + 631 = 53635
Step 86: 53635 + 631 = 54266
Step 87: 54266 + 631 = 54897
Step 88: 54897 + 631 = 55528
Step 89: 55528 + 631 = 56159
Step 90: 56159 + 631 = 56790
Step 91: 56790 + 631 = 57421
Step 92: 57421 + 631 = 58052
Step 93: 58052 + 631 = 58683
Step 94: 58683 + 631 = 59314
Step 95: 59314 + 631 = 59945
Step 96: 59945 + 631 = 60576
Step 97: 60576 + 631 = 61207
Step 98: 61207 + 631 = 61838
Step 99: 61838 + 631 = 62469
Step 100: 62469 + 631 = 63100
Step 101: 63100 + 631 = 63731
Step 102: 63731 + 631 = 64362
Step 103: 64362 + 631 = 64993
Step 104: 64993 + 631 = 65624
Step 105: 65624 + 631 = 66255
Step 106: 66255 + 631 = 66886
Step 107: 66886 + 631 = 67517
Step 108: 67517 + 631 = 68148
Step 109: 68148 + 631 = 68779
Step 110: 68779 + 631 = 69410
Step 111: 69410 + 631 = 70041
Step 112: 70041 + 631 = 70672
Step 113: 70672 + 631 = 71303
Step 114: 71303 + 631 = 71934
Step 115: 71934 + 631 = 72565
Step 116: 72565 + 631 = 73196
Step 117: 73196 + 631 = 73827
Step 118: 73827 + 631 = 74458
Step 119: 74458 + 631 = 75089
Step 120: 75089 + 631 = 75720
Step 121: 75720 + 631 = 76351
Step 122: 76351 + 631 = 76982
Step 123: 76982 + 631 = 77613
Step 124: 77613 + 631 = 78244
Step 125: 78244 + 631 = 78875
Step 126: 78875 + 631 = 79506
Step 127: 79506 + 631 = 80137
Step 128: 80137 + 631 = 80768
Step 129: 80768 + 631 = 81399

So, 631*129 = 81399