OK, let's work through this together. We're starting with 42 and we're going to multiply it by 485, which means we add 42 to itself 485 times.
Step 1: 0 + 42 = 42
Step 2: 42 + 42 = 84
Step 3: 84 + 42 = 126
Step 4: 126 + 42 = 168
Step 5: 168 + 42 = 210
Step 6: 210 + 42 = 252
Step 7: 252 + 42 = 294
Step 8: 294 + 42 = 336
Step 9: 336 + 42 = 378
Step 10: 378 + 42 = 420
Step 11: 420 + 42 = 462
Step 12: 462 + 42 = 504
Step 13: 504 + 42 = 546
Step 14: 546 + 42 = 588
Step 15: 588 + 42 = 630
Step 16: 630 + 42 = 672
Step 17: 672 + 42 = 714
Step 18: 714 + 42 = 756
Step 19: 756 + 42 = 798
Step 20: 798 + 42 = 840
Step 21: 840 + 42 = 882
Step 22: 882 + 42 = 924
Step 23: 924 + 42 = 966
Step 24: 966 + 42 = 1008
Step 25: 1008 + 42 = 1050
Step 26: 1050 + 42 = 1092
Step 27: 1092 + 42 = 1134
Step 28: 1134 + 42 = 1176
Step 29: 1176 + 42 = 1218
Step 30: 1218 + 42 = 1260
Step 31: 1260 + 42 = 1302
Step 32: 1302 + 42 = 1344
Step 33: 1344 + 42 = 1386
Step 34: 1386 + 42 = 1428
Step 35: 1428 + 42 = 1470
Step 36: 1470 + 42 = 1512
Step 37: 1512 + 42 = 1554
Step 38: 1554 + 42 = 1596
Step 39: 1596 + 42 = 1638
Step 40: 1638 + 42 = 1680
Step 41: 1680 + 42 = 1722
Step 42: 1722 + 42 = 1764
Step 43: 1764 + 42 = 1806
Step 44: 1806 + 42 = 1848
Step 45: 1848 + 42 = 1890
Step 46: 1890 + 42 = 1932
Step 47: 1932 + 42 = 1974
Step 48: 1974 + 42 = 2016
Step 49: 2016 + 42 = 2058
Step 50: 2058 + 42 = 2100
Step 51: 2100 + 42 = 2142
Step 52: 2142 + 42 = 2184
Step 53: 2184 + 42 = 2226
Step 54: 2226 + 42 = 2268
Step 55: 2268 + 42 = 2310
Step 56: 2310 + 42 = 2352
Step 57: 2352 + 42 = 2394
Step 58: 2394 + 42 = 2436
Step 59: 2436 + 42 = 2478
Step 60: 2478 + 42 = 2520
Step 61: 2520 + 42 = 2562
Step 62: 2562 + 42 = 2604
Step 63: 2604 + 42 = 2646
Step 64: 2646 + 42 = 2688
Step 65: 2688 + 42 = 2730
Step 66: 2730 + 42 = 2772
Step 67: 2772 + 42 = 2814
Step 68: 2814 + 42 = 2856
Step 69: 2856 + 42 = 2898
Step 70: 2898 + 42 = 2940
Step 71: 2940 + 42 = 2982
Step 72: 2982 + 42 = 3024
Step 73: 3024 + 42 = 3066
Step 74: 3066 + 42 = 3108
Step 75: 3108 + 42 = 3150
Step 76: 3150 + 42 = 3192
Step 77: 3192 + 42 = 3234
Step 78: 3234 + 42 = 3276
Step 79: 3276 + 42 = 3318
Step 80: 3318 + 42 = 3360
Step 81: 3360 + 42 = 3402
Step 82: 3402 + 42 = 3444
Step 83: 3444 + 42 = 3486
Step 84: 3486 + 42 = 3528
Step 85: 3528 + 42 = 3570
Step 86: 3570 + 42 = 3612
Step 87: 3612 + 42 = 3654
Step 88: 3654 + 42 = 3696
Step 89: 3696 + 42 = 3738
Step 90: 3738 + 42 = 3780
Step 91: 3780 + 42 = 3822
Step 92: 3822 + 42 = 3864
Step 93: 3864 + 42 = 3906
Step 94: 3906 + 42 = 3948
Step 95: 3948 + 42 = 3990
Step 96: 3990 + 42 = 4032
Step 97: 4032 + 42 = 4074
Step 98: 4074 + 42 = 4116
Step 99: 4116 + 42 = 4158
Step 100: 4158 + 42 = 4200
Step 101: 4200 + 42 = 4242
Step 102: 4242 + 42 = 4284
Step 103: 4284 + 42 = 4326
Step 104: 4326 + 42 = 4368
Step 105: 4368 + 42 = 4410
Step 106: 4410 + 42 = 4452
Step 107: 4452 + 42 = 4494
Step 108: 4494 + 42 = 4536
Step 109: 4536 + 42 = 4578
Step 110: 4578 + 42 = 4620
Step 111: 4620 + 42 = 4662
Step 112: 4662 + 42 = 4704
Step 113: 4704 + 42 = 4746
Step 114: 4746 + 42 = 4788
Step 115: 4788 + 42 = 4830
Step 116: 4830 + 42 = 4872
Step 117: 4872 + 42 = 4914
Step 118: 4914 + 42 = 4956
Step 119: 4956 + 42 = 4998
Step 120: 4998 + 42 = 5040
Step 121: 5040 + 42 = 5082
Step 122: 5082 + 42 = 5124
Step 123: 5124 + 42 = 5166
Step 124: 5166 + 42 = 5208
Step 125: 5208 + 42 = 5250
Step 126: 5250 + 42 = 5292
Step 127: 5292 + 42 = 5334
Step 128: 5334 + 42 = 5376
Step 129: 5376 + 42 = 5418
Step 130: 5418 + 42 = 5460
Step 131: 5460 + 42 = 5502
Step 132: 5502 + 42 = 5544
Step 133: 5544 + 42 = 5586
Step 134: 5586 + 42 = 5628
Step 135: 5628 + 42 = 5670
Step 136: 5670 + 42 = 5712
Step 137: 5712 + 42 = 5754
Step 138: 5754 + 42 = 5796
Step 139: 5796 + 42 = 5838
Step 140: 5838 + 42 = 5880
Step 141: 5880 + 42 = 5922
Step 142: 5922 + 42 = 5964
Step 143: 5964 + 42 = 6006
Step 144: 6006 + 42 = 6048
Step 145: 6048 + 42 = 6090
Step 146: 6090 + 42 = 6132
Step 147: 6132 + 42 = 6174
Step 148: 6174 + 42 = 6216
Step 149: 6216 + 42 = 6258
Step 150: 6258 + 42 = 6300
Step 151: 6300 + 42 = 6342
Step 152: 6342 + 42 = 6384
Step 153: 6384 + 42 = 6426
Step 154: 6426 + 42 = 6468
Step 155: 6468 + 42 = 6510
Step 156: 6510 + 42 = 6552
Step 157: 6552 + 42 = 6594
Step 158: 6594 + 42 = 6636
Step 159: 6636 + 42 = 6678
Step 160: 6678 + 42 = 6720
Step 161: 6720 + 42 = 6762
Step 162: 6762 + 42 = 6804
Step 163: 6804 + 42 = 6846
Step 164: 6846 + 42 = 6888
Step 165: 6888 + 42 = 6930
Step 166: 6930 + 42 = 6972
Step 167: 6972 + 42 = 7014
Step 168: 7014 + 42 = 7056
Step 169: 7056 + 42 = 7098
Step 170: 7098 + 42 = 7140
Step 171: 7140 + 42 = 7182
Step 172: 7182 + 42 = 7224
Step 173: 7224 + 42 = 7266
Step 174: 7266 + 42 = 7308
Step 175: 7308 + 42 = 7350
Step 176: 7350 + 42 = 7392
Step 177: 7392 + 42 = 7434
Step 178: 7434 + 42 = 7476
Step 179: 7476 + 42 = 7518
Step 180: 7518 + 42 = 7560
Step 181: 7560 + 42 = 7602
Step 182: 7602 + 42 = 7644
Step 183: 7644 + 42 = 7686
Step 184: 7686 + 42 = 7728
Step 185: 7728 + 42 = 7770
Step 186: 7770 + 42 = 7812
Step 187: 7812 + 42 = 7854
Step 188: 7854 + 42 = 7896
Step 189: 7896 + 42 = 7938
Step 190: 7938 + 42 = 7980
Step 191: 7980 + 42 = 8022
Step 192: 8022 + 42 = 8064
Step 193: 8064 + 42 = 8106
Step 194: 8106 + 42 = 8148
Step 195: 8148 + 42 = 8190
Step 196: 8190 + 42 = 8232
Step 197: 8232 + 42 = 8274
Step 198: 8274 + 42 = 8316
Step 199: 8316 + 42 = 8358
Step 200: 8358 + 42 = 8400
Step 201: 8400 + 42 = 8442
Step 202: 8442 + 42 = 8484
Step 203: 8484 + 42 = 8526
Step 204: 8526 + 42 = 8568
Step 205: 8568 + 42 = 8610
Step 206: 8610 + 42 = 8652
Step 207: 8652 + 42 = 8694
Step 208: 8694 + 42 = 8736
Step 209: 8736 + 42 = 8778
Step 210: 8778 + 42 = 8820
Step 211: 8820 + 42 = 8862
Step 212: 8862 + 42 = 8904
Step 213: 8904 + 42 = 8946
Step 214: 8946 + 42 = 8988
Step 215: 8988 + 42 = 9030
Step 216: 9030 + 42 = 9072
Step 217: 9072 + 42 = 9114
Step 218: 9114 + 42 = 9156
Step 219: 9156 + 42 = 9198
Step 220: 9198 + 42 = 9240
Step 221: 9240 + 42 = 9282
Step 222: 9282 + 42 = 9324
Step 223: 9324 + 42 = 9366
Step 224: 9366 + 42 = 9408
Step 225: 9408 + 42 = 9450
Step 226: 9450 + 42 = 9492
Step 227: 9492 + 42 = 9534
Step 228: 9534 + 42 = 9576
Step 229: 9576 + 42 = 9618
Step 230: 9618 + 42 = 9660
Step 231: 9660 + 42 = 9702
Step 232: 9702 + 42 = 9744
Step 233: 9744 + 42 = 9786
Step 234: 9786 + 42 = 9828
Step 235: 9828 + 42 = 9870
Step 236: 9870 + 42 = 9912
Step 237: 9912 + 42 = 9954
Step 238: 9954 + 42 = 9996
Step 239: 9996 + 42 = 10038
Step 240: 10038 + 42 = 10080
Step 241: 10080 + 42 = 10122
Step 242: 10122 + 42 = 10164
Step 243: 10164 + 42 = 10206
Step 244: 10206 + 42 = 10248
Step 245: 10248 + 42 = 10290
Step 246: 10290 + 42 = 10332
Step 247: 10332 + 42 = 10374
Step 248: 10374 + 42 = 10416
Step 249: 10416 + 42 = 10458
Step 250: 10458 + 42 = 10500
Step 251: 10500 + 42 = 10542
Step 252: 10542 + 42 = 10584
Step 253: 10584 + 42 = 10626
Step 254: 10626 + 42 = 10668
Step 255: 10668 + 42 = 10710
Step 256: 10710 + 42 = 10752
Step 257: 10752 + 42 = 10794
Step 258: 10794 + 42 = 10836
Step 259: 10836 + 42 = 10878
Step 260: 10878 + 42 = 10920
Step 261: 10920 + 42 = 10962
Step 262: 10962 + 42 = 11004
Step 263: 11004 + 42 = 11046
Step 264: 11046 + 42 = 11088
Step 265: 11088 + 42 = 11130
Step 266: 11130 + 42 = 11172
Step 267: 11172 + 42 = 11214
Step 268: 11214 + 42 = 11256
Step 269: 11256 + 42 = 11298
Step 270: 11298 + 42 = 11340
Step 271: 11340 + 42 = 11382
Step 272: 11382 + 42 = 11424
Step 273: 11424 + 42 = 11466
Step 274: 11466 + 42 = 11508
Step 275: 11508 + 42 = 11550
Step 276: 11550 + 42 = 11592
Step 277: 11592 + 42 = 11634
Step 278: 11634 + 42 = 11676
Step 279: 11676 + 42 = 11718
Step 280: 11718 + 42 = 11760
Step 281: 11760 + 42 = 11802
Step 282: 11802 + 42 = 11844
Step 283: 11844 + 42 = 11886
Step 284: 11886 + 42 = 11928
Step 285: 11928 + 42 = 11970
Step 286: 11970 + 42 = 12012
Step 287: 12012 + 42 = 12054
Step 288: 12054 + 42 = 12096
Step 289: 12096 + 42 = 12138
Step 290: 12138 + 42 = 12180
Step 291: 12180 + 42 = 12222
Step 292: 12222 + 42 = 12264
Step 293: 12264 + 42 = 12306
Step 294: 12306 + 42 = 12348
Step 295: 12348 + 42 = 12390
Step 296: 12390 + 42 = 12432
Step 297: 12432 + 42 = 12474
Step 298: 12474 + 42 = 12516
Step 299: 12516 + 42 = 12558
Step 300: 12558 + 42 = 12600
Step 301: 12600 + 42 = 12642
Step 302: 12642 + 42 = 12684
Step 303: 12684 + 42 = 12726
Step 304: 12726 + 42 = 12768
Step 305: 12768 + 42 = 12810
Step 306: 12810 + 42 = 12852
Step 307: 12852 + 42 = 12894
Step 308: 12894 + 42 = 12936
Step 309: 12936 + 42 = 12978
Step 310: 12978 + 42 = 13020
Step 311: 13020 + 42 = 13062
Step 312: 13062 + 42 = 13104
Step 313: 13104 + 42 = 13146
Step 314: 13146 + 42 = 13188
Step 315: 13188 + 42 = 13230
Step 316: 13230 + 42 = 13272
Step 317: 13272 + 42 = 13314
Step 318: 13314 + 42 = 13356
Step 319: 13356 + 42 = 13398
Step 320: 13398 + 42 = 13440
Step 321: 13440 + 42 = 13482
Step 322: 13482 + 42 = 13524
Step 323: 13524 + 42 = 13566
Step 324: 13566 + 42 = 13608
Step 325: 13608 + 42 = 13650
Step 326: 13650 + 42 = 13692
Step 327: 13692 + 42 = 13734
Step 328: 13734 + 42 = 13776
Step 329: 13776 + 42 = 13818
Step 330: 13818 + 42 = 13860
Step 331: 13860 + 42 = 13902
Step 332: 13902 + 42 = 13944
Step 333: 13944 + 42 = 13986
Step 334: 13986 + 42 = 14028
Step 335: 14028 + 42 = 14070
Step 336: 14070 + 42 = 14112
Step 337: 14112 + 42 = 14154
Step 338: 14154 + 42 = 14196
Step 339: 14196 + 42 = 14238
Step 340: 14238 + 42 = 14280
Step 341: 14280 + 42 = 14322
Step 342: 14322 + 42 = 14364
Step 343: 14364 + 42 = 14406
Step 344: 14406 + 42 = 14448
Step 345: 14448 + 42 = 14490
Step 346: 14490 + 42 = 14532
Step 347: 14532 + 42 = 14574
Step 348: 14574 + 42 = 14616
Step 349: 14616 + 42 = 14658
Step 350: 14658 + 42 = 14700
Step 351: 14700 + 42 = 14742
Step 352: 14742 + 42 = 14784
Step 353: 14784 + 42 = 14826
Step 354: 14826 + 42 = 14868
Step 355: 14868 + 42 = 14910
Step 356: 14910 + 42 = 14952
Step 357: 14952 + 42 = 14994
Step 358: 14994 + 42 = 15036
Step 359: 15036 + 42 = 15078
Step 360: 15078 + 42 = 15120
Step 361: 15120 + 42 = 15162
Step 362: 15162 + 42 = 15204
Step 363: 15204 + 42 = 15246
Step 364: 15246 + 42 = 15288
Step 365: 15288 + 42 = 15330
Step 366: 15330 + 42 = 15372
Step 367: 15372 + 42 = 15414
Step 368: 15414 + 42 = 15456
Step 369: 15456 + 42 = 15498
Step 370: 15498 + 42 = 15540
Step 371: 15540 + 42 = 15582
Step 372: 15582 + 42 = 15624
Step 373: 15624 + 42 = 15666
Step 374: 15666 + 42 = 15708
Step 375: 15708 + 42 = 15750
Step 376: 15750 + 42 = 15792
Step 377: 15792 + 42 = 15834
Step 378: 15834 + 42 = 15876
Step 379: 15876 + 42 = 15918
Step 380: 15918 + 42 = 15960
Step 381: 15960 + 42 = 16002
Step 382: 16002 + 42 = 16044
Step 383: 16044 + 42 = 16086
Step 384: 16086 + 42 = 16128
Step 385: 16128 + 42 = 16170
Step 386: 16170 + 42 = 16212
Step 387: 16212 + 42 = 16254
Step 388: 16254 + 42 = 16296
Step 389: 16296 + 42 = 16338
Step 390: 16338 + 42 = 16380
Step 391: 16380 + 42 = 16422
Step 392: 16422 + 42 = 16464
Step 393: 16464 + 42 = 16506
Step 394: 16506 + 42 = 16548
Step 395: 16548 + 42 = 16590
Step 396: 16590 + 42 = 16632
Step 397: 16632 + 42 = 16674
Step 398: 16674 + 42 = 16716
Step 399: 16716 + 42 = 16758
Step 400: 16758 + 42 = 16800
Step 401: 16800 + 42 = 16842
Step 402: 16842 + 42 = 16884
Step 403: 16884 + 42 = 16926
Step 404: 16926 + 42 = 16968
Step 405: 16968 + 42 = 17010
Step 406: 17010 + 42 = 17052
Step 407: 17052 + 42 = 17094
Step 408: 17094 + 42 = 17136
Step 409: 17136 + 42 = 17178
Step 410: 17178 + 42 = 17220
Step 411: 17220 + 42 = 17262
Step 412: 17262 + 42 = 17304
Step 413: 17304 + 42 = 17346
Step 414: 17346 + 42 = 17388
Step 415: 17388 + 42 = 17430
Step 416: 17430 + 42 = 17472
Step 417: 17472 + 42 = 17514
Step 418: 17514 + 42 = 17556
Step 419: 17556 + 42 = 17598
Step 420: 17598 + 42 = 17640
Step 421: 17640 + 42 = 17682
Step 422: 17682 + 42 = 17724
Step 423: 17724 + 42 = 17766
Step 424: 17766 + 42 = 17808
Step 425: 17808 + 42 = 17850
Step 426: 17850 + 42 = 17892
Step 427: 17892 + 42 = 17934
Step 428: 17934 + 42 = 17976
Step 429: 17976 + 42 = 18018
Step 430: 18018 + 42 = 18060
Step 431: 18060 + 42 = 18102
Step 432: 18102 + 42 = 18144
Step 433: 18144 + 42 = 18186
Step 434: 18186 + 42 = 18228
Step 435: 18228 + 42 = 18270
Step 436: 18270 + 42 = 18312
Step 437: 18312 + 42 = 18354
Step 438: 18354 + 42 = 18396
Step 439: 18396 + 42 = 18438
Step 440: 18438 + 42 = 18480
Step 441: 18480 + 42 = 18522
Step 442: 18522 + 42 = 18564
Step 443: 18564 + 42 = 18606
Step 444: 18606 + 42 = 18648
Step 445: 18648 + 42 = 18690
Step 446: 18690 + 42 = 18732
Step 447: 18732 + 42 = 18774
Step 448: 18774 + 42 = 18816
Step 449: 18816 + 42 = 18858
Step 450: 18858 + 42 = 18900
Step 451: 18900 + 42 = 18942
Step 452: 18942 + 42 = 18984
Step 453: 18984 + 42 = 19026
Step 454: 19026 + 42 = 19068
Step 455: 19068 + 42 = 19110
Step 456: 19110 + 42 = 19152
Step 457: 19152 + 42 = 19194
Step 458: 19194 + 42 = 19236
Step 459: 19236 + 42 = 19278
Step 460: 19278 + 42 = 19320
Step 461: 19320 + 42 = 19362
Step 462: 19362 + 42 = 19404
Step 463: 19404 + 42 = 19446
Step 464: 19446 + 42 = 19488
Step 465: 19488 + 42 = 19530
Step 466: 19530 + 42 = 19572
Step 467: 19572 + 42 = 19614
Step 468: 19614 + 42 = 19656
Step 469: 19656 + 42 = 19698
Step 470: 19698 + 42 = 19740
Step 471: 19740 + 42 = 19782
Step 472: 19782 + 42 = 19824
Step 473: 19824 + 42 = 19866
Step 474: 19866 + 42 = 19908
Step 475: 19908 + 42 = 19950
Step 476: 19950 + 42 = 19992
Step 477: 19992 + 42 = 20034
Step 478: 20034 + 42 = 20076
Step 479: 20076 + 42 = 20118
Step 480: 20118 + 42 = 20160
Step 481: 20160 + 42 = 20202
Step 482: 20202 + 42 = 20244
Step 483: 20244 + 42 = 20286
Step 484: 20286 + 42 = 20328
Step 485: 20328 + 42 = 20370

So, 42*485 = 20370