OK, let's crack this. We're given 735 and our task is to multiply it by 172. Essentially, we'll be adding 735 to itself 172 times.
Step 1: 0 + 735 = 735
Step 2: 735 + 735 = 1470
Step 3: 1470 + 735 = 2205
Step 4: 2205 + 735 = 2940
Step 5: 2940 + 735 = 3675
Step 6: 3675 + 735 = 4410
Step 7: 4410 + 735 = 5145
Step 8: 5145 + 735 = 5880
Step 9: 5880 + 735 = 6615
Step 10: 6615 + 735 = 7350
Step 11: 7350 + 735 = 8085
Step 12: 8085 + 735 = 8820
Step 13: 8820 + 735 = 9555
Step 14: 9555 + 735 = 10290
Step 15: 10290 + 735 = 11025
Step 16: 11025 + 735 = 11760
Step 17: 11760 + 735 = 12495
Step 18: 12495 + 735 = 13230
Step 19: 13230 + 735 = 13965
Step 20: 13965 + 735 = 14700
Step 21: 14700 + 735 = 15435
Step 22: 15435 + 735 = 16170
Step 23: 16170 + 735 = 16905
Step 24: 16905 + 735 = 17640
Step 25: 17640 + 735 = 18375
Step 26: 18375 + 735 = 19110
Step 27: 19110 + 735 = 19845
Step 28: 19845 + 735 = 20580
Step 29: 20580 + 735 = 21315
Step 30: 21315 + 735 = 22050
Step 31: 22050 + 735 = 22785
Step 32: 22785 + 735 = 23520
Step 33: 23520 + 735 = 24255
Step 34: 24255 + 735 = 24990
Step 35: 24990 + 735 = 25725
Step 36: 25725 + 735 = 26460
Step 37: 26460 + 735 = 27195
Step 38: 27195 + 735 = 27930
Step 39: 27930 + 735 = 28665
Step 40: 28665 + 735 = 29400
Step 41: 29400 + 735 = 30135
Step 42: 30135 + 735 = 30870
Step 43: 30870 + 735 = 31605
Step 44: 31605 + 735 = 32340
Step 45: 32340 + 735 = 33075
Step 46: 33075 + 735 = 33810
Step 47: 33810 + 735 = 34545
Step 48: 34545 + 735 = 35280
Step 49: 35280 + 735 = 36015
Step 50: 36015 + 735 = 36750
Step 51: 36750 + 735 = 37485
Step 52: 37485 + 735 = 38220
Step 53: 38220 + 735 = 38955
Step 54: 38955 + 735 = 39690
Step 55: 39690 + 735 = 40425
Step 56: 40425 + 735 = 41160
Step 57: 41160 + 735 = 41895
Step 58: 41895 + 735 = 42630
Step 59: 42630 + 735 = 43365
Step 60: 43365 + 735 = 44100
Step 61: 44100 + 735 = 44835
Step 62: 44835 + 735 = 45570
Step 63: 45570 + 735 = 46305
Step 64: 46305 + 735 = 47040
Step 65: 47040 + 735 = 47775
Step 66: 47775 + 735 = 48510
Step 67: 48510 + 735 = 49245
Step 68: 49245 + 735 = 49980
Step 69: 49980 + 735 = 50715
Step 70: 50715 + 735 = 51450
Step 71: 51450 + 735 = 52185
Step 72: 52185 + 735 = 52920
Step 73: 52920 + 735 = 53655
Step 74: 53655 + 735 = 54390
Step 75: 54390 + 735 = 55125
Step 76: 55125 + 735 = 55860
Step 77: 55860 + 735 = 56595
Step 78: 56595 + 735 = 57330
Step 79: 57330 + 735 = 58065
Step 80: 58065 + 735 = 58800
Step 81: 58800 + 735 = 59535
Step 82: 59535 + 735 = 60270
Step 83: 60270 + 735 = 61005
Step 84: 61005 + 735 = 61740
Step 85: 61740 + 735 = 62475
Step 86: 62475 + 735 = 63210
Step 87: 63210 + 735 = 63945
Step 88: 63945 + 735 = 64680
Step 89: 64680 + 735 = 65415
Step 90: 65415 + 735 = 66150
Step 91: 66150 + 735 = 66885
Step 92: 66885 + 735 = 67620
Step 93: 67620 + 735 = 68355
Step 94: 68355 + 735 = 69090
Step 95: 69090 + 735 = 69825
Step 96: 69825 + 735 = 70560
Step 97: 70560 + 735 = 71295
Step 98: 71295 + 735 = 72030
Step 99: 72030 + 735 = 72765
Step 100: 72765 + 735 = 73500
Step 101: 73500 + 735 = 74235
Step 102: 74235 + 735 = 74970
Step 103: 74970 + 735 = 75705
Step 104: 75705 + 735 = 76440
Step 105: 76440 + 735 = 77175
Step 106: 77175 + 735 = 77910
Step 107: 77910 + 735 = 78645
Step 108: 78645 + 735 = 79380
Step 109: 79380 + 735 = 80115
Step 110: 80115 + 735 = 80850
Step 111: 80850 + 735 = 81585
Step 112: 81585 + 735 = 82320
Step 113: 82320 + 735 = 83055
Step 114: 83055 + 735 = 83790
Step 115: 83790 + 735 = 84525
Step 116: 84525 + 735 = 85260
Step 117: 85260 + 735 = 85995
Step 118: 85995 + 735 = 86730
Step 119: 86730 + 735 = 87465
Step 120: 87465 + 735 = 88200
Step 121: 88200 + 735 = 88935
Step 122: 88935 + 735 = 89670
Step 123: 89670 + 735 = 90405
Step 124: 90405 + 735 = 91140
Step 125: 91140 + 735 = 91875
Step 126: 91875 + 735 = 92610
Step 127: 92610 + 735 = 93345
Step 128: 93345 + 735 = 94080
Step 129: 94080 + 735 = 94815
Step 130: 94815 + 735 = 95550
Step 131: 95550 + 735 = 96285
Step 132: 96285 + 735 = 97020
Step 133: 97020 + 735 = 97755
Step 134: 97755 + 735 = 98490
Step 135: 98490 + 735 = 99225
Step 136: 99225 + 735 = 99960
Step 137: 99960 + 735 = 100695
Step 138: 100695 + 735 = 101430
Step 139: 101430 + 735 = 102165
Step 140: 102165 + 735 = 102900
Step 141: 102900 + 735 = 103635
Step 142: 103635 + 735 = 104370
Step 143: 104370 + 735 = 105105
Step 144: 105105 + 735 = 105840
Step 145: 105840 + 735 = 106575
Step 146: 106575 + 735 = 107310
Step 147: 107310 + 735 = 108045
Step 148: 108045 + 735 = 108780
Step 149: 108780 + 735 = 109515
Step 150: 109515 + 735 = 110250
Step 151: 110250 + 735 = 110985
Step 152: 110985 + 735 = 111720
Step 153: 111720 + 735 = 112455
Step 154: 112455 + 735 = 113190
Step 155: 113190 + 735 = 113925
Step 156: 113925 + 735 = 114660
Step 157: 114660 + 735 = 115395
Step 158: 115395 + 735 = 116130
Step 159: 116130 + 735 = 116865
Step 160: 116865 + 735 = 117600
Step 161: 117600 + 735 = 118335
Step 162: 118335 + 735 = 119070
Step 163: 119070 + 735 = 119805
Step 164: 119805 + 735 = 120540
Step 165: 120540 + 735 = 121275
Step 166: 121275 + 735 = 122010
Step 167: 122010 + 735 = 122745
Step 168: 122745 + 735 = 123480
Step 169: 123480 + 735 = 124215
Step 170: 124215 + 735 = 124950
Step 171: 124950 + 735 = 125685
Step 172: 125685 + 735 = 126420

So, 735*172 = 126420