Let's get this math done. We have 811 and we're going to multiply it by 171. This is the same as taking 811 and adding it to itself 171 times.
Step 1: 0 + 811 = 811
Step 2: 811 + 811 = 1622
Step 3: 1622 + 811 = 2433
Step 4: 2433 + 811 = 3244
Step 5: 3244 + 811 = 4055
Step 6: 4055 + 811 = 4866
Step 7: 4866 + 811 = 5677
Step 8: 5677 + 811 = 6488
Step 9: 6488 + 811 = 7299
Step 10: 7299 + 811 = 8110
Step 11: 8110 + 811 = 8921
Step 12: 8921 + 811 = 9732
Step 13: 9732 + 811 = 10543
Step 14: 10543 + 811 = 11354
Step 15: 11354 + 811 = 12165
Step 16: 12165 + 811 = 12976
Step 17: 12976 + 811 = 13787
Step 18: 13787 + 811 = 14598
Step 19: 14598 + 811 = 15409
Step 20: 15409 + 811 = 16220
Step 21: 16220 + 811 = 17031
Step 22: 17031 + 811 = 17842
Step 23: 17842 + 811 = 18653
Step 24: 18653 + 811 = 19464
Step 25: 19464 + 811 = 20275
Step 26: 20275 + 811 = 21086
Step 27: 21086 + 811 = 21897
Step 28: 21897 + 811 = 22708
Step 29: 22708 + 811 = 23519
Step 30: 23519 + 811 = 24330
Step 31: 24330 + 811 = 25141
Step 32: 25141 + 811 = 25952
Step 33: 25952 + 811 = 26763
Step 34: 26763 + 811 = 27574
Step 35: 27574 + 811 = 28385
Step 36: 28385 + 811 = 29196
Step 37: 29196 + 811 = 30007
Step 38: 30007 + 811 = 30818
Step 39: 30818 + 811 = 31629
Step 40: 31629 + 811 = 32440
Step 41: 32440 + 811 = 33251
Step 42: 33251 + 811 = 34062
Step 43: 34062 + 811 = 34873
Step 44: 34873 + 811 = 35684
Step 45: 35684 + 811 = 36495
Step 46: 36495 + 811 = 37306
Step 47: 37306 + 811 = 38117
Step 48: 38117 + 811 = 38928
Step 49: 38928 + 811 = 39739
Step 50: 39739 + 811 = 40550
Step 51: 40550 + 811 = 41361
Step 52: 41361 + 811 = 42172
Step 53: 42172 + 811 = 42983
Step 54: 42983 + 811 = 43794
Step 55: 43794 + 811 = 44605
Step 56: 44605 + 811 = 45416
Step 57: 45416 + 811 = 46227
Step 58: 46227 + 811 = 47038
Step 59: 47038 + 811 = 47849
Step 60: 47849 + 811 = 48660
Step 61: 48660 + 811 = 49471
Step 62: 49471 + 811 = 50282
Step 63: 50282 + 811 = 51093
Step 64: 51093 + 811 = 51904
Step 65: 51904 + 811 = 52715
Step 66: 52715 + 811 = 53526
Step 67: 53526 + 811 = 54337
Step 68: 54337 + 811 = 55148
Step 69: 55148 + 811 = 55959
Step 70: 55959 + 811 = 56770
Step 71: 56770 + 811 = 57581
Step 72: 57581 + 811 = 58392
Step 73: 58392 + 811 = 59203
Step 74: 59203 + 811 = 60014
Step 75: 60014 + 811 = 60825
Step 76: 60825 + 811 = 61636
Step 77: 61636 + 811 = 62447
Step 78: 62447 + 811 = 63258
Step 79: 63258 + 811 = 64069
Step 80: 64069 + 811 = 64880
Step 81: 64880 + 811 = 65691
Step 82: 65691 + 811 = 66502
Step 83: 66502 + 811 = 67313
Step 84: 67313 + 811 = 68124
Step 85: 68124 + 811 = 68935
Step 86: 68935 + 811 = 69746
Step 87: 69746 + 811 = 70557
Step 88: 70557 + 811 = 71368
Step 89: 71368 + 811 = 72179
Step 90: 72179 + 811 = 72990
Step 91: 72990 + 811 = 73801
Step 92: 73801 + 811 = 74612
Step 93: 74612 + 811 = 75423
Step 94: 75423 + 811 = 76234
Step 95: 76234 + 811 = 77045
Step 96: 77045 + 811 = 77856
Step 97: 77856 + 811 = 78667
Step 98: 78667 + 811 = 79478
Step 99: 79478 + 811 = 80289
Step 100: 80289 + 811 = 81100
Step 101: 81100 + 811 = 81911
Step 102: 81911 + 811 = 82722
Step 103: 82722 + 811 = 83533
Step 104: 83533 + 811 = 84344
Step 105: 84344 + 811 = 85155
Step 106: 85155 + 811 = 85966
Step 107: 85966 + 811 = 86777
Step 108: 86777 + 811 = 87588
Step 109: 87588 + 811 = 88399
Step 110: 88399 + 811 = 89210
Step 111: 89210 + 811 = 90021
Step 112: 90021 + 811 = 90832
Step 113: 90832 + 811 = 91643
Step 114: 91643 + 811 = 92454
Step 115: 92454 + 811 = 93265
Step 116: 93265 + 811 = 94076
Step 117: 94076 + 811 = 94887
Step 118: 94887 + 811 = 95698
Step 119: 95698 + 811 = 96509
Step 120: 96509 + 811 = 97320
Step 121: 97320 + 811 = 98131
Step 122: 98131 + 811 = 98942
Step 123: 98942 + 811 = 99753
Step 124: 99753 + 811 = 100564
Step 125: 100564 + 811 = 101375
Step 126: 101375 + 811 = 102186
Step 127: 102186 + 811 = 102997
Step 128: 102997 + 811 = 103808
Step 129: 103808 + 811 = 104619
Step 130: 104619 + 811 = 105430
Step 131: 105430 + 811 = 106241
Step 132: 106241 + 811 = 107052
Step 133: 107052 + 811 = 107863
Step 134: 107863 + 811 = 108674
Step 135: 108674 + 811 = 109485
Step 136: 109485 + 811 = 110296
Step 137: 110296 + 811 = 111107
Step 138: 111107 + 811 = 111918
Step 139: 111918 + 811 = 112729
Step 140: 112729 + 811 = 113540
Step 141: 113540 + 811 = 114351
Step 142: 114351 + 811 = 115162
Step 143: 115162 + 811 = 115973
Step 144: 115973 + 811 = 116784
Step 145: 116784 + 811 = 117595
Step 146: 117595 + 811 = 118406
Step 147: 118406 + 811 = 119217
Step 148: 119217 + 811 = 120028
Step 149: 120028 + 811 = 120839
Step 150: 120839 + 811 = 121650
Step 151: 121650 + 811 = 122461
Step 152: 122461 + 811 = 123272
Step 153: 123272 + 811 = 124083
Step 154: 124083 + 811 = 124894
Step 155: 124894 + 811 = 125705
Step 156: 125705 + 811 = 126516
Step 157: 126516 + 811 = 127327
Step 158: 127327 + 811 = 128138
Step 159: 128138 + 811 = 128949
Step 160: 128949 + 811 = 129760
Step 161: 129760 + 811 = 130571
Step 162: 130571 + 811 = 131382
Step 163: 131382 + 811 = 132193
Step 164: 132193 + 811 = 133004
Step 165: 133004 + 811 = 133815
Step 166: 133815 + 811 = 134626
Step 167: 134626 + 811 = 135437
Step 168: 135437 + 811 = 136248
Step 169: 136248 + 811 = 137059
Step 170: 137059 + 811 = 137870
Step 171: 137870 + 811 = 138681

So, 811*171 = 138681