OK, let's crack this. We're given 905 and our task is to multiply it by 231. Essentially, we'll be adding 905 to itself 231 times.
Step 1: 0 + 905 = 905
Step 2: 905 + 905 = 1810
Step 3: 1810 + 905 = 2715
Step 4: 2715 + 905 = 3620
Step 5: 3620 + 905 = 4525
Step 6: 4525 + 905 = 5430
Step 7: 5430 + 905 = 6335
Step 8: 6335 + 905 = 7240
Step 9: 7240 + 905 = 8145
Step 10: 8145 + 905 = 9050
Step 11: 9050 + 905 = 9955
Step 12: 9955 + 905 = 10860
Step 13: 10860 + 905 = 11765
Step 14: 11765 + 905 = 12670
Step 15: 12670 + 905 = 13575
Step 16: 13575 + 905 = 14480
Step 17: 14480 + 905 = 15385
Step 18: 15385 + 905 = 16290
Step 19: 16290 + 905 = 17195
Step 20: 17195 + 905 = 18100
Step 21: 18100 + 905 = 19005
Step 22: 19005 + 905 = 19910
Step 23: 19910 + 905 = 20815
Step 24: 20815 + 905 = 21720
Step 25: 21720 + 905 = 22625
Step 26: 22625 + 905 = 23530
Step 27: 23530 + 905 = 24435
Step 28: 24435 + 905 = 25340
Step 29: 25340 + 905 = 26245
Step 30: 26245 + 905 = 27150
Step 31: 27150 + 905 = 28055
Step 32: 28055 + 905 = 28960
Step 33: 28960 + 905 = 29865
Step 34: 29865 + 905 = 30770
Step 35: 30770 + 905 = 31675
Step 36: 31675 + 905 = 32580
Step 37: 32580 + 905 = 33485
Step 38: 33485 + 905 = 34390
Step 39: 34390 + 905 = 35295
Step 40: 35295 + 905 = 36200
Step 41: 36200 + 905 = 37105
Step 42: 37105 + 905 = 38010
Step 43: 38010 + 905 = 38915
Step 44: 38915 + 905 = 39820
Step 45: 39820 + 905 = 40725
Step 46: 40725 + 905 = 41630
Step 47: 41630 + 905 = 42535
Step 48: 42535 + 905 = 43440
Step 49: 43440 + 905 = 44345
Step 50: 44345 + 905 = 45250
Step 51: 45250 + 905 = 46155
Step 52: 46155 + 905 = 47060
Step 53: 47060 + 905 = 47965
Step 54: 47965 + 905 = 48870
Step 55: 48870 + 905 = 49775
Step 56: 49775 + 905 = 50680
Step 57: 50680 + 905 = 51585
Step 58: 51585 + 905 = 52490
Step 59: 52490 + 905 = 53395
Step 60: 53395 + 905 = 54300
Step 61: 54300 + 905 = 55205
Step 62: 55205 + 905 = 56110
Step 63: 56110 + 905 = 57015
Step 64: 57015 + 905 = 57920
Step 65: 57920 + 905 = 58825
Step 66: 58825 + 905 = 59730
Step 67: 59730 + 905 = 60635
Step 68: 60635 + 905 = 61540
Step 69: 61540 + 905 = 62445
Step 70: 62445 + 905 = 63350
Step 71: 63350 + 905 = 64255
Step 72: 64255 + 905 = 65160
Step 73: 65160 + 905 = 66065
Step 74: 66065 + 905 = 66970
Step 75: 66970 + 905 = 67875
Step 76: 67875 + 905 = 68780
Step 77: 68780 + 905 = 69685
Step 78: 69685 + 905 = 70590
Step 79: 70590 + 905 = 71495
Step 80: 71495 + 905 = 72400
Step 81: 72400 + 905 = 73305
Step 82: 73305 + 905 = 74210
Step 83: 74210 + 905 = 75115
Step 84: 75115 + 905 = 76020
Step 85: 76020 + 905 = 76925
Step 86: 76925 + 905 = 77830
Step 87: 77830 + 905 = 78735
Step 88: 78735 + 905 = 79640
Step 89: 79640 + 905 = 80545
Step 90: 80545 + 905 = 81450
Step 91: 81450 + 905 = 82355
Step 92: 82355 + 905 = 83260
Step 93: 83260 + 905 = 84165
Step 94: 84165 + 905 = 85070
Step 95: 85070 + 905 = 85975
Step 96: 85975 + 905 = 86880
Step 97: 86880 + 905 = 87785
Step 98: 87785 + 905 = 88690
Step 99: 88690 + 905 = 89595
Step 100: 89595 + 905 = 90500
Step 101: 90500 + 905 = 91405
Step 102: 91405 + 905 = 92310
Step 103: 92310 + 905 = 93215
Step 104: 93215 + 905 = 94120
Step 105: 94120 + 905 = 95025
Step 106: 95025 + 905 = 95930
Step 107: 95930 + 905 = 96835
Step 108: 96835 + 905 = 97740
Step 109: 97740 + 905 = 98645
Step 110: 98645 + 905 = 99550
Step 111: 99550 + 905 = 100455
Step 112: 100455 + 905 = 101360
Step 113: 101360 + 905 = 102265
Step 114: 102265 + 905 = 103170
Step 115: 103170 + 905 = 104075
Step 116: 104075 + 905 = 104980
Step 117: 104980 + 905 = 105885
Step 118: 105885 + 905 = 106790
Step 119: 106790 + 905 = 107695
Step 120: 107695 + 905 = 108600
Step 121: 108600 + 905 = 109505
Step 122: 109505 + 905 = 110410
Step 123: 110410 + 905 = 111315
Step 124: 111315 + 905 = 112220
Step 125: 112220 + 905 = 113125
Step 126: 113125 + 905 = 114030
Step 127: 114030 + 905 = 114935
Step 128: 114935 + 905 = 115840
Step 129: 115840 + 905 = 116745
Step 130: 116745 + 905 = 117650
Step 131: 117650 + 905 = 118555
Step 132: 118555 + 905 = 119460
Step 133: 119460 + 905 = 120365
Step 134: 120365 + 905 = 121270
Step 135: 121270 + 905 = 122175
Step 136: 122175 + 905 = 123080
Step 137: 123080 + 905 = 123985
Step 138: 123985 + 905 = 124890
Step 139: 124890 + 905 = 125795
Step 140: 125795 + 905 = 126700
Step 141: 126700 + 905 = 127605
Step 142: 127605 + 905 = 128510
Step 143: 128510 + 905 = 129415
Step 144: 129415 + 905 = 130320
Step 145: 130320 + 905 = 131225
Step 146: 131225 + 905 = 132130
Step 147: 132130 + 905 = 133035
Step 148: 133035 + 905 = 133940
Step 149: 133940 + 905 = 134845
Step 150: 134845 + 905 = 135750
Step 151: 135750 + 905 = 136655
Step 152: 136655 + 905 = 137560
Step 153: 137560 + 905 = 138465
Step 154: 138465 + 905 = 139370
Step 155: 139370 + 905 = 140275
Step 156: 140275 + 905 = 141180
Step 157: 141180 + 905 = 142085
Step 158: 142085 + 905 = 142990
Step 159: 142990 + 905 = 143895
Step 160: 143895 + 905 = 144800
Step 161: 144800 + 905 = 145705
Step 162: 145705 + 905 = 146610
Step 163: 146610 + 905 = 147515
Step 164: 147515 + 905 = 148420
Step 165: 148420 + 905 = 149325
Step 166: 149325 + 905 = 150230
Step 167: 150230 + 905 = 151135
Step 168: 151135 + 905 = 152040
Step 169: 152040 + 905 = 152945
Step 170: 152945 + 905 = 153850
Step 171: 153850 + 905 = 154755
Step 172: 154755 + 905 = 155660
Step 173: 155660 + 905 = 156565
Step 174: 156565 + 905 = 157470
Step 175: 157470 + 905 = 158375
Step 176: 158375 + 905 = 159280
Step 177: 159280 + 905 = 160185
Step 178: 160185 + 905 = 161090
Step 179: 161090 + 905 = 161995
Step 180: 161995 + 905 = 162900
Step 181: 162900 + 905 = 163805
Step 182: 163805 + 905 = 164710
Step 183: 164710 + 905 = 165615
Step 184: 165615 + 905 = 166520
Step 185: 166520 + 905 = 167425
Step 186: 167425 + 905 = 168330
Step 187: 168330 + 905 = 169235
Step 188: 169235 + 905 = 170140
Step 189: 170140 + 905 = 171045
Step 190: 171045 + 905 = 171950
Step 191: 171950 + 905 = 172855
Step 192: 172855 + 905 = 173760
Step 193: 173760 + 905 = 174665
Step 194: 174665 + 905 = 175570
Step 195: 175570 + 905 = 176475
Step 196: 176475 + 905 = 177380
Step 197: 177380 + 905 = 178285
Step 198: 178285 + 905 = 179190
Step 199: 179190 + 905 = 180095
Step 200: 180095 + 905 = 181000
Step 201: 181000 + 905 = 181905
Step 202: 181905 + 905 = 182810
Step 203: 182810 + 905 = 183715
Step 204: 183715 + 905 = 184620
Step 205: 184620 + 905 = 185525
Step 206: 185525 + 905 = 186430
Step 207: 186430 + 905 = 187335
Step 208: 187335 + 905 = 188240
Step 209: 188240 + 905 = 189145
Step 210: 189145 + 905 = 190050
Step 211: 190050 + 905 = 190955
Step 212: 190955 + 905 = 191860
Step 213: 191860 + 905 = 192765
Step 214: 192765 + 905 = 193670
Step 215: 193670 + 905 = 194575
Step 216: 194575 + 905 = 195480
Step 217: 195480 + 905 = 196385
Step 218: 196385 + 905 = 197290
Step 219: 197290 + 905 = 198195
Step 220: 198195 + 905 = 199100
Step 221: 199100 + 905 = 200005
Step 222: 200005 + 905 = 200910
Step 223: 200910 + 905 = 201815
Step 224: 201815 + 905 = 202720
Step 225: 202720 + 905 = 203625
Step 226: 203625 + 905 = 204530
Step 227: 204530 + 905 = 205435
Step 228: 205435 + 905 = 206340
Step 229: 206340 + 905 = 207245
Step 230: 207245 + 905 = 208150
Step 231: 208150 + 905 = 209055

So, 905*231 = 209055