Alright, let's solve this math problem step by step. First, we have the number 159. 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 159 and add it to itself 129 times.
Step 1: 0 + 159 = 159
Step 2: 159 + 159 = 318
Step 3: 318 + 159 = 477
Step 4: 477 + 159 = 636
Step 5: 636 + 159 = 795
Step 6: 795 + 159 = 954
Step 7: 954 + 159 = 1113
Step 8: 1113 + 159 = 1272
Step 9: 1272 + 159 = 1431
Step 10: 1431 + 159 = 1590
Step 11: 1590 + 159 = 1749
Step 12: 1749 + 159 = 1908
Step 13: 1908 + 159 = 2067
Step 14: 2067 + 159 = 2226
Step 15: 2226 + 159 = 2385
Step 16: 2385 + 159 = 2544
Step 17: 2544 + 159 = 2703
Step 18: 2703 + 159 = 2862
Step 19: 2862 + 159 = 3021
Step 20: 3021 + 159 = 3180
Step 21: 3180 + 159 = 3339
Step 22: 3339 + 159 = 3498
Step 23: 3498 + 159 = 3657
Step 24: 3657 + 159 = 3816
Step 25: 3816 + 159 = 3975
Step 26: 3975 + 159 = 4134
Step 27: 4134 + 159 = 4293
Step 28: 4293 + 159 = 4452
Step 29: 4452 + 159 = 4611
Step 30: 4611 + 159 = 4770
Step 31: 4770 + 159 = 4929
Step 32: 4929 + 159 = 5088
Step 33: 5088 + 159 = 5247
Step 34: 5247 + 159 = 5406
Step 35: 5406 + 159 = 5565
Step 36: 5565 + 159 = 5724
Step 37: 5724 + 159 = 5883
Step 38: 5883 + 159 = 6042
Step 39: 6042 + 159 = 6201
Step 40: 6201 + 159 = 6360
Step 41: 6360 + 159 = 6519
Step 42: 6519 + 159 = 6678
Step 43: 6678 + 159 = 6837
Step 44: 6837 + 159 = 6996
Step 45: 6996 + 159 = 7155
Step 46: 7155 + 159 = 7314
Step 47: 7314 + 159 = 7473
Step 48: 7473 + 159 = 7632
Step 49: 7632 + 159 = 7791
Step 50: 7791 + 159 = 7950
Step 51: 7950 + 159 = 8109
Step 52: 8109 + 159 = 8268
Step 53: 8268 + 159 = 8427
Step 54: 8427 + 159 = 8586
Step 55: 8586 + 159 = 8745
Step 56: 8745 + 159 = 8904
Step 57: 8904 + 159 = 9063
Step 58: 9063 + 159 = 9222
Step 59: 9222 + 159 = 9381
Step 60: 9381 + 159 = 9540
Step 61: 9540 + 159 = 9699
Step 62: 9699 + 159 = 9858
Step 63: 9858 + 159 = 10017
Step 64: 10017 + 159 = 10176
Step 65: 10176 + 159 = 10335
Step 66: 10335 + 159 = 10494
Step 67: 10494 + 159 = 10653
Step 68: 10653 + 159 = 10812
Step 69: 10812 + 159 = 10971
Step 70: 10971 + 159 = 11130
Step 71: 11130 + 159 = 11289
Step 72: 11289 + 159 = 11448
Step 73: 11448 + 159 = 11607
Step 74: 11607 + 159 = 11766
Step 75: 11766 + 159 = 11925
Step 76: 11925 + 159 = 12084
Step 77: 12084 + 159 = 12243
Step 78: 12243 + 159 = 12402
Step 79: 12402 + 159 = 12561
Step 80: 12561 + 159 = 12720
Step 81: 12720 + 159 = 12879
Step 82: 12879 + 159 = 13038
Step 83: 13038 + 159 = 13197
Step 84: 13197 + 159 = 13356
Step 85: 13356 + 159 = 13515
Step 86: 13515 + 159 = 13674
Step 87: 13674 + 159 = 13833
Step 88: 13833 + 159 = 13992
Step 89: 13992 + 159 = 14151
Step 90: 14151 + 159 = 14310
Step 91: 14310 + 159 = 14469
Step 92: 14469 + 159 = 14628
Step 93: 14628 + 159 = 14787
Step 94: 14787 + 159 = 14946
Step 95: 14946 + 159 = 15105
Step 96: 15105 + 159 = 15264
Step 97: 15264 + 159 = 15423
Step 98: 15423 + 159 = 15582
Step 99: 15582 + 159 = 15741
Step 100: 15741 + 159 = 15900
Step 101: 15900 + 159 = 16059
Step 102: 16059 + 159 = 16218
Step 103: 16218 + 159 = 16377
Step 104: 16377 + 159 = 16536
Step 105: 16536 + 159 = 16695
Step 106: 16695 + 159 = 16854
Step 107: 16854 + 159 = 17013
Step 108: 17013 + 159 = 17172
Step 109: 17172 + 159 = 17331
Step 110: 17331 + 159 = 17490
Step 111: 17490 + 159 = 17649
Step 112: 17649 + 159 = 17808
Step 113: 17808 + 159 = 17967
Step 114: 17967 + 159 = 18126
Step 115: 18126 + 159 = 18285
Step 116: 18285 + 159 = 18444
Step 117: 18444 + 159 = 18603
Step 118: 18603 + 159 = 18762
Step 119: 18762 + 159 = 18921
Step 120: 18921 + 159 = 19080
Step 121: 19080 + 159 = 19239
Step 122: 19239 + 159 = 19398
Step 123: 19398 + 159 = 19557
Step 124: 19557 + 159 = 19716
Step 125: 19716 + 159 = 19875
Step 126: 19875 + 159 = 20034
Step 127: 20034 + 159 = 20193
Step 128: 20193 + 159 = 20352
Step 129: 20352 + 159 = 20511

So, 159*129 = 20511