OK, let's crack this. We're given 855 and our task is to multiply it by 255. Essentially, we'll be adding 855 to itself 255 times.
Step 1: 0 + 855 = 855
Step 2: 855 + 855 = 1710
Step 3: 1710 + 855 = 2565
Step 4: 2565 + 855 = 3420
Step 5: 3420 + 855 = 4275
Step 6: 4275 + 855 = 5130
Step 7: 5130 + 855 = 5985
Step 8: 5985 + 855 = 6840
Step 9: 6840 + 855 = 7695
Step 10: 7695 + 855 = 8550
Step 11: 8550 + 855 = 9405
Step 12: 9405 + 855 = 10260
Step 13: 10260 + 855 = 11115
Step 14: 11115 + 855 = 11970
Step 15: 11970 + 855 = 12825
Step 16: 12825 + 855 = 13680
Step 17: 13680 + 855 = 14535
Step 18: 14535 + 855 = 15390
Step 19: 15390 + 855 = 16245
Step 20: 16245 + 855 = 17100
Step 21: 17100 + 855 = 17955
Step 22: 17955 + 855 = 18810
Step 23: 18810 + 855 = 19665
Step 24: 19665 + 855 = 20520
Step 25: 20520 + 855 = 21375
Step 26: 21375 + 855 = 22230
Step 27: 22230 + 855 = 23085
Step 28: 23085 + 855 = 23940
Step 29: 23940 + 855 = 24795
Step 30: 24795 + 855 = 25650
Step 31: 25650 + 855 = 26505
Step 32: 26505 + 855 = 27360
Step 33: 27360 + 855 = 28215
Step 34: 28215 + 855 = 29070
Step 35: 29070 + 855 = 29925
Step 36: 29925 + 855 = 30780
Step 37: 30780 + 855 = 31635
Step 38: 31635 + 855 = 32490
Step 39: 32490 + 855 = 33345
Step 40: 33345 + 855 = 34200
Step 41: 34200 + 855 = 35055
Step 42: 35055 + 855 = 35910
Step 43: 35910 + 855 = 36765
Step 44: 36765 + 855 = 37620
Step 45: 37620 + 855 = 38475
Step 46: 38475 + 855 = 39330
Step 47: 39330 + 855 = 40185
Step 48: 40185 + 855 = 41040
Step 49: 41040 + 855 = 41895
Step 50: 41895 + 855 = 42750
Step 51: 42750 + 855 = 43605
Step 52: 43605 + 855 = 44460
Step 53: 44460 + 855 = 45315
Step 54: 45315 + 855 = 46170
Step 55: 46170 + 855 = 47025
Step 56: 47025 + 855 = 47880
Step 57: 47880 + 855 = 48735
Step 58: 48735 + 855 = 49590
Step 59: 49590 + 855 = 50445
Step 60: 50445 + 855 = 51300
Step 61: 51300 + 855 = 52155
Step 62: 52155 + 855 = 53010
Step 63: 53010 + 855 = 53865
Step 64: 53865 + 855 = 54720
Step 65: 54720 + 855 = 55575
Step 66: 55575 + 855 = 56430
Step 67: 56430 + 855 = 57285
Step 68: 57285 + 855 = 58140
Step 69: 58140 + 855 = 58995
Step 70: 58995 + 855 = 59850
Step 71: 59850 + 855 = 60705
Step 72: 60705 + 855 = 61560
Step 73: 61560 + 855 = 62415
Step 74: 62415 + 855 = 63270
Step 75: 63270 + 855 = 64125
Step 76: 64125 + 855 = 64980
Step 77: 64980 + 855 = 65835
Step 78: 65835 + 855 = 66690
Step 79: 66690 + 855 = 67545
Step 80: 67545 + 855 = 68400
Step 81: 68400 + 855 = 69255
Step 82: 69255 + 855 = 70110
Step 83: 70110 + 855 = 70965
Step 84: 70965 + 855 = 71820
Step 85: 71820 + 855 = 72675
Step 86: 72675 + 855 = 73530
Step 87: 73530 + 855 = 74385
Step 88: 74385 + 855 = 75240
Step 89: 75240 + 855 = 76095
Step 90: 76095 + 855 = 76950
Step 91: 76950 + 855 = 77805
Step 92: 77805 + 855 = 78660
Step 93: 78660 + 855 = 79515
Step 94: 79515 + 855 = 80370
Step 95: 80370 + 855 = 81225
Step 96: 81225 + 855 = 82080
Step 97: 82080 + 855 = 82935
Step 98: 82935 + 855 = 83790
Step 99: 83790 + 855 = 84645
Step 100: 84645 + 855 = 85500
Step 101: 85500 + 855 = 86355
Step 102: 86355 + 855 = 87210
Step 103: 87210 + 855 = 88065
Step 104: 88065 + 855 = 88920
Step 105: 88920 + 855 = 89775
Step 106: 89775 + 855 = 90630
Step 107: 90630 + 855 = 91485
Step 108: 91485 + 855 = 92340
Step 109: 92340 + 855 = 93195
Step 110: 93195 + 855 = 94050
Step 111: 94050 + 855 = 94905
Step 112: 94905 + 855 = 95760
Step 113: 95760 + 855 = 96615
Step 114: 96615 + 855 = 97470
Step 115: 97470 + 855 = 98325
Step 116: 98325 + 855 = 99180
Step 117: 99180 + 855 = 100035
Step 118: 100035 + 855 = 100890
Step 119: 100890 + 855 = 101745
Step 120: 101745 + 855 = 102600
Step 121: 102600 + 855 = 103455
Step 122: 103455 + 855 = 104310
Step 123: 104310 + 855 = 105165
Step 124: 105165 + 855 = 106020
Step 125: 106020 + 855 = 106875
Step 126: 106875 + 855 = 107730
Step 127: 107730 + 855 = 108585
Step 128: 108585 + 855 = 109440
Step 129: 109440 + 855 = 110295
Step 130: 110295 + 855 = 111150
Step 131: 111150 + 855 = 112005
Step 132: 112005 + 855 = 112860
Step 133: 112860 + 855 = 113715
Step 134: 113715 + 855 = 114570
Step 135: 114570 + 855 = 115425
Step 136: 115425 + 855 = 116280
Step 137: 116280 + 855 = 117135
Step 138: 117135 + 855 = 117990
Step 139: 117990 + 855 = 118845
Step 140: 118845 + 855 = 119700
Step 141: 119700 + 855 = 120555
Step 142: 120555 + 855 = 121410
Step 143: 121410 + 855 = 122265
Step 144: 122265 + 855 = 123120
Step 145: 123120 + 855 = 123975
Step 146: 123975 + 855 = 124830
Step 147: 124830 + 855 = 125685
Step 148: 125685 + 855 = 126540
Step 149: 126540 + 855 = 127395
Step 150: 127395 + 855 = 128250
Step 151: 128250 + 855 = 129105
Step 152: 129105 + 855 = 129960
Step 153: 129960 + 855 = 130815
Step 154: 130815 + 855 = 131670
Step 155: 131670 + 855 = 132525
Step 156: 132525 + 855 = 133380
Step 157: 133380 + 855 = 134235
Step 158: 134235 + 855 = 135090
Step 159: 135090 + 855 = 135945
Step 160: 135945 + 855 = 136800
Step 161: 136800 + 855 = 137655
Step 162: 137655 + 855 = 138510
Step 163: 138510 + 855 = 139365
Step 164: 139365 + 855 = 140220
Step 165: 140220 + 855 = 141075
Step 166: 141075 + 855 = 141930
Step 167: 141930 + 855 = 142785
Step 168: 142785 + 855 = 143640
Step 169: 143640 + 855 = 144495
Step 170: 144495 + 855 = 145350
Step 171: 145350 + 855 = 146205
Step 172: 146205 + 855 = 147060
Step 173: 147060 + 855 = 147915
Step 174: 147915 + 855 = 148770
Step 175: 148770 + 855 = 149625
Step 176: 149625 + 855 = 150480
Step 177: 150480 + 855 = 151335
Step 178: 151335 + 855 = 152190
Step 179: 152190 + 855 = 153045
Step 180: 153045 + 855 = 153900
Step 181: 153900 + 855 = 154755
Step 182: 154755 + 855 = 155610
Step 183: 155610 + 855 = 156465
Step 184: 156465 + 855 = 157320
Step 185: 157320 + 855 = 158175
Step 186: 158175 + 855 = 159030
Step 187: 159030 + 855 = 159885
Step 188: 159885 + 855 = 160740
Step 189: 160740 + 855 = 161595
Step 190: 161595 + 855 = 162450
Step 191: 162450 + 855 = 163305
Step 192: 163305 + 855 = 164160
Step 193: 164160 + 855 = 165015
Step 194: 165015 + 855 = 165870
Step 195: 165870 + 855 = 166725
Step 196: 166725 + 855 = 167580
Step 197: 167580 + 855 = 168435
Step 198: 168435 + 855 = 169290
Step 199: 169290 + 855 = 170145
Step 200: 170145 + 855 = 171000
Step 201: 171000 + 855 = 171855
Step 202: 171855 + 855 = 172710
Step 203: 172710 + 855 = 173565
Step 204: 173565 + 855 = 174420
Step 205: 174420 + 855 = 175275
Step 206: 175275 + 855 = 176130
Step 207: 176130 + 855 = 176985
Step 208: 176985 + 855 = 177840
Step 209: 177840 + 855 = 178695
Step 210: 178695 + 855 = 179550
Step 211: 179550 + 855 = 180405
Step 212: 180405 + 855 = 181260
Step 213: 181260 + 855 = 182115
Step 214: 182115 + 855 = 182970
Step 215: 182970 + 855 = 183825
Step 216: 183825 + 855 = 184680
Step 217: 184680 + 855 = 185535
Step 218: 185535 + 855 = 186390
Step 219: 186390 + 855 = 187245
Step 220: 187245 + 855 = 188100
Step 221: 188100 + 855 = 188955
Step 222: 188955 + 855 = 189810
Step 223: 189810 + 855 = 190665
Step 224: 190665 + 855 = 191520
Step 225: 191520 + 855 = 192375
Step 226: 192375 + 855 = 193230
Step 227: 193230 + 855 = 194085
Step 228: 194085 + 855 = 194940
Step 229: 194940 + 855 = 195795
Step 230: 195795 + 855 = 196650
Step 231: 196650 + 855 = 197505
Step 232: 197505 + 855 = 198360
Step 233: 198360 + 855 = 199215
Step 234: 199215 + 855 = 200070
Step 235: 200070 + 855 = 200925
Step 236: 200925 + 855 = 201780
Step 237: 201780 + 855 = 202635
Step 238: 202635 + 855 = 203490
Step 239: 203490 + 855 = 204345
Step 240: 204345 + 855 = 205200
Step 241: 205200 + 855 = 206055
Step 242: 206055 + 855 = 206910
Step 243: 206910 + 855 = 207765
Step 244: 207765 + 855 = 208620
Step 245: 208620 + 855 = 209475
Step 246: 209475 + 855 = 210330
Step 247: 210330 + 855 = 211185
Step 248: 211185 + 855 = 212040
Step 249: 212040 + 855 = 212895
Step 250: 212895 + 855 = 213750
Step 251: 213750 + 855 = 214605
Step 252: 214605 + 855 = 215460
Step 253: 215460 + 855 = 216315
Step 254: 216315 + 855 = 217170
Step 255: 217170 + 855 = 218025

So, 855*255 = 218025