Sure thing, let's get straight to it. We start with 871 and we're going to multiply it by 142, which means adding 871 to itself 142 times.
Step 1: 0 + 871 = 871
Step 2: 871 + 871 = 1742
Step 3: 1742 + 871 = 2613
Step 4: 2613 + 871 = 3484
Step 5: 3484 + 871 = 4355
Step 6: 4355 + 871 = 5226
Step 7: 5226 + 871 = 6097
Step 8: 6097 + 871 = 6968
Step 9: 6968 + 871 = 7839
Step 10: 7839 + 871 = 8710
Step 11: 8710 + 871 = 9581
Step 12: 9581 + 871 = 10452
Step 13: 10452 + 871 = 11323
Step 14: 11323 + 871 = 12194
Step 15: 12194 + 871 = 13065
Step 16: 13065 + 871 = 13936
Step 17: 13936 + 871 = 14807
Step 18: 14807 + 871 = 15678
Step 19: 15678 + 871 = 16549
Step 20: 16549 + 871 = 17420
Step 21: 17420 + 871 = 18291
Step 22: 18291 + 871 = 19162
Step 23: 19162 + 871 = 20033
Step 24: 20033 + 871 = 20904
Step 25: 20904 + 871 = 21775
Step 26: 21775 + 871 = 22646
Step 27: 22646 + 871 = 23517
Step 28: 23517 + 871 = 24388
Step 29: 24388 + 871 = 25259
Step 30: 25259 + 871 = 26130
Step 31: 26130 + 871 = 27001
Step 32: 27001 + 871 = 27872
Step 33: 27872 + 871 = 28743
Step 34: 28743 + 871 = 29614
Step 35: 29614 + 871 = 30485
Step 36: 30485 + 871 = 31356
Step 37: 31356 + 871 = 32227
Step 38: 32227 + 871 = 33098
Step 39: 33098 + 871 = 33969
Step 40: 33969 + 871 = 34840
Step 41: 34840 + 871 = 35711
Step 42: 35711 + 871 = 36582
Step 43: 36582 + 871 = 37453
Step 44: 37453 + 871 = 38324
Step 45: 38324 + 871 = 39195
Step 46: 39195 + 871 = 40066
Step 47: 40066 + 871 = 40937
Step 48: 40937 + 871 = 41808
Step 49: 41808 + 871 = 42679
Step 50: 42679 + 871 = 43550
Step 51: 43550 + 871 = 44421
Step 52: 44421 + 871 = 45292
Step 53: 45292 + 871 = 46163
Step 54: 46163 + 871 = 47034
Step 55: 47034 + 871 = 47905
Step 56: 47905 + 871 = 48776
Step 57: 48776 + 871 = 49647
Step 58: 49647 + 871 = 50518
Step 59: 50518 + 871 = 51389
Step 60: 51389 + 871 = 52260
Step 61: 52260 + 871 = 53131
Step 62: 53131 + 871 = 54002
Step 63: 54002 + 871 = 54873
Step 64: 54873 + 871 = 55744
Step 65: 55744 + 871 = 56615
Step 66: 56615 + 871 = 57486
Step 67: 57486 + 871 = 58357
Step 68: 58357 + 871 = 59228
Step 69: 59228 + 871 = 60099
Step 70: 60099 + 871 = 60970
Step 71: 60970 + 871 = 61841
Step 72: 61841 + 871 = 62712
Step 73: 62712 + 871 = 63583
Step 74: 63583 + 871 = 64454
Step 75: 64454 + 871 = 65325
Step 76: 65325 + 871 = 66196
Step 77: 66196 + 871 = 67067
Step 78: 67067 + 871 = 67938
Step 79: 67938 + 871 = 68809
Step 80: 68809 + 871 = 69680
Step 81: 69680 + 871 = 70551
Step 82: 70551 + 871 = 71422
Step 83: 71422 + 871 = 72293
Step 84: 72293 + 871 = 73164
Step 85: 73164 + 871 = 74035
Step 86: 74035 + 871 = 74906
Step 87: 74906 + 871 = 75777
Step 88: 75777 + 871 = 76648
Step 89: 76648 + 871 = 77519
Step 90: 77519 + 871 = 78390
Step 91: 78390 + 871 = 79261
Step 92: 79261 + 871 = 80132
Step 93: 80132 + 871 = 81003
Step 94: 81003 + 871 = 81874
Step 95: 81874 + 871 = 82745
Step 96: 82745 + 871 = 83616
Step 97: 83616 + 871 = 84487
Step 98: 84487 + 871 = 85358
Step 99: 85358 + 871 = 86229
Step 100: 86229 + 871 = 87100
Step 101: 87100 + 871 = 87971
Step 102: 87971 + 871 = 88842
Step 103: 88842 + 871 = 89713
Step 104: 89713 + 871 = 90584
Step 105: 90584 + 871 = 91455
Step 106: 91455 + 871 = 92326
Step 107: 92326 + 871 = 93197
Step 108: 93197 + 871 = 94068
Step 109: 94068 + 871 = 94939
Step 110: 94939 + 871 = 95810
Step 111: 95810 + 871 = 96681
Step 112: 96681 + 871 = 97552
Step 113: 97552 + 871 = 98423
Step 114: 98423 + 871 = 99294
Step 115: 99294 + 871 = 100165
Step 116: 100165 + 871 = 101036
Step 117: 101036 + 871 = 101907
Step 118: 101907 + 871 = 102778
Step 119: 102778 + 871 = 103649
Step 120: 103649 + 871 = 104520
Step 121: 104520 + 871 = 105391
Step 122: 105391 + 871 = 106262
Step 123: 106262 + 871 = 107133
Step 124: 107133 + 871 = 108004
Step 125: 108004 + 871 = 108875
Step 126: 108875 + 871 = 109746
Step 127: 109746 + 871 = 110617
Step 128: 110617 + 871 = 111488
Step 129: 111488 + 871 = 112359
Step 130: 112359 + 871 = 113230
Step 131: 113230 + 871 = 114101
Step 132: 114101 + 871 = 114972
Step 133: 114972 + 871 = 115843
Step 134: 115843 + 871 = 116714
Step 135: 116714 + 871 = 117585
Step 136: 117585 + 871 = 118456
Step 137: 118456 + 871 = 119327
Step 138: 119327 + 871 = 120198
Step 139: 120198 + 871 = 121069
Step 140: 121069 + 871 = 121940
Step 141: 121940 + 871 = 122811
Step 142: 122811 + 871 = 123682

So, 871*142 = 123682