Sure thing, let's get straight to it. We start with 875 and we're going to multiply it by 129, which means adding 875 to itself 129 times.
Step 1: 0 + 875 = 875
Step 2: 875 + 875 = 1750
Step 3: 1750 + 875 = 2625
Step 4: 2625 + 875 = 3500
Step 5: 3500 + 875 = 4375
Step 6: 4375 + 875 = 5250
Step 7: 5250 + 875 = 6125
Step 8: 6125 + 875 = 7000
Step 9: 7000 + 875 = 7875
Step 10: 7875 + 875 = 8750
Step 11: 8750 + 875 = 9625
Step 12: 9625 + 875 = 10500
Step 13: 10500 + 875 = 11375
Step 14: 11375 + 875 = 12250
Step 15: 12250 + 875 = 13125
Step 16: 13125 + 875 = 14000
Step 17: 14000 + 875 = 14875
Step 18: 14875 + 875 = 15750
Step 19: 15750 + 875 = 16625
Step 20: 16625 + 875 = 17500
Step 21: 17500 + 875 = 18375
Step 22: 18375 + 875 = 19250
Step 23: 19250 + 875 = 20125
Step 24: 20125 + 875 = 21000
Step 25: 21000 + 875 = 21875
Step 26: 21875 + 875 = 22750
Step 27: 22750 + 875 = 23625
Step 28: 23625 + 875 = 24500
Step 29: 24500 + 875 = 25375
Step 30: 25375 + 875 = 26250
Step 31: 26250 + 875 = 27125
Step 32: 27125 + 875 = 28000
Step 33: 28000 + 875 = 28875
Step 34: 28875 + 875 = 29750
Step 35: 29750 + 875 = 30625
Step 36: 30625 + 875 = 31500
Step 37: 31500 + 875 = 32375
Step 38: 32375 + 875 = 33250
Step 39: 33250 + 875 = 34125
Step 40: 34125 + 875 = 35000
Step 41: 35000 + 875 = 35875
Step 42: 35875 + 875 = 36750
Step 43: 36750 + 875 = 37625
Step 44: 37625 + 875 = 38500
Step 45: 38500 + 875 = 39375
Step 46: 39375 + 875 = 40250
Step 47: 40250 + 875 = 41125
Step 48: 41125 + 875 = 42000
Step 49: 42000 + 875 = 42875
Step 50: 42875 + 875 = 43750
Step 51: 43750 + 875 = 44625
Step 52: 44625 + 875 = 45500
Step 53: 45500 + 875 = 46375
Step 54: 46375 + 875 = 47250
Step 55: 47250 + 875 = 48125
Step 56: 48125 + 875 = 49000
Step 57: 49000 + 875 = 49875
Step 58: 49875 + 875 = 50750
Step 59: 50750 + 875 = 51625
Step 60: 51625 + 875 = 52500
Step 61: 52500 + 875 = 53375
Step 62: 53375 + 875 = 54250
Step 63: 54250 + 875 = 55125
Step 64: 55125 + 875 = 56000
Step 65: 56000 + 875 = 56875
Step 66: 56875 + 875 = 57750
Step 67: 57750 + 875 = 58625
Step 68: 58625 + 875 = 59500
Step 69: 59500 + 875 = 60375
Step 70: 60375 + 875 = 61250
Step 71: 61250 + 875 = 62125
Step 72: 62125 + 875 = 63000
Step 73: 63000 + 875 = 63875
Step 74: 63875 + 875 = 64750
Step 75: 64750 + 875 = 65625
Step 76: 65625 + 875 = 66500
Step 77: 66500 + 875 = 67375
Step 78: 67375 + 875 = 68250
Step 79: 68250 + 875 = 69125
Step 80: 69125 + 875 = 70000
Step 81: 70000 + 875 = 70875
Step 82: 70875 + 875 = 71750
Step 83: 71750 + 875 = 72625
Step 84: 72625 + 875 = 73500
Step 85: 73500 + 875 = 74375
Step 86: 74375 + 875 = 75250
Step 87: 75250 + 875 = 76125
Step 88: 76125 + 875 = 77000
Step 89: 77000 + 875 = 77875
Step 90: 77875 + 875 = 78750
Step 91: 78750 + 875 = 79625
Step 92: 79625 + 875 = 80500
Step 93: 80500 + 875 = 81375
Step 94: 81375 + 875 = 82250
Step 95: 82250 + 875 = 83125
Step 96: 83125 + 875 = 84000
Step 97: 84000 + 875 = 84875
Step 98: 84875 + 875 = 85750
Step 99: 85750 + 875 = 86625
Step 100: 86625 + 875 = 87500
Step 101: 87500 + 875 = 88375
Step 102: 88375 + 875 = 89250
Step 103: 89250 + 875 = 90125
Step 104: 90125 + 875 = 91000
Step 105: 91000 + 875 = 91875
Step 106: 91875 + 875 = 92750
Step 107: 92750 + 875 = 93625
Step 108: 93625 + 875 = 94500
Step 109: 94500 + 875 = 95375
Step 110: 95375 + 875 = 96250
Step 111: 96250 + 875 = 97125
Step 112: 97125 + 875 = 98000
Step 113: 98000 + 875 = 98875
Step 114: 98875 + 875 = 99750
Step 115: 99750 + 875 = 100625
Step 116: 100625 + 875 = 101500
Step 117: 101500 + 875 = 102375
Step 118: 102375 + 875 = 103250
Step 119: 103250 + 875 = 104125
Step 120: 104125 + 875 = 105000
Step 121: 105000 + 875 = 105875
Step 122: 105875 + 875 = 106750
Step 123: 106750 + 875 = 107625
Step 124: 107625 + 875 = 108500
Step 125: 108500 + 875 = 109375
Step 126: 109375 + 875 = 110250
Step 127: 110250 + 875 = 111125
Step 128: 111125 + 875 = 112000
Step 129: 112000 + 875 = 112875

So, 875*129 = 112875