OK, let's work through this together. We're starting with 842 and we're going to multiply it by 394, which means we add 842 to itself 394 times.
Step 1: 0 + 842 = 842
Step 2: 842 + 842 = 1684
Step 3: 1684 + 842 = 2526
Step 4: 2526 + 842 = 3368
Step 5: 3368 + 842 = 4210
Step 6: 4210 + 842 = 5052
Step 7: 5052 + 842 = 5894
Step 8: 5894 + 842 = 6736
Step 9: 6736 + 842 = 7578
Step 10: 7578 + 842 = 8420
Step 11: 8420 + 842 = 9262
Step 12: 9262 + 842 = 10104
Step 13: 10104 + 842 = 10946
Step 14: 10946 + 842 = 11788
Step 15: 11788 + 842 = 12630
Step 16: 12630 + 842 = 13472
Step 17: 13472 + 842 = 14314
Step 18: 14314 + 842 = 15156
Step 19: 15156 + 842 = 15998
Step 20: 15998 + 842 = 16840
Step 21: 16840 + 842 = 17682
Step 22: 17682 + 842 = 18524
Step 23: 18524 + 842 = 19366
Step 24: 19366 + 842 = 20208
Step 25: 20208 + 842 = 21050
Step 26: 21050 + 842 = 21892
Step 27: 21892 + 842 = 22734
Step 28: 22734 + 842 = 23576
Step 29: 23576 + 842 = 24418
Step 30: 24418 + 842 = 25260
Step 31: 25260 + 842 = 26102
Step 32: 26102 + 842 = 26944
Step 33: 26944 + 842 = 27786
Step 34: 27786 + 842 = 28628
Step 35: 28628 + 842 = 29470
Step 36: 29470 + 842 = 30312
Step 37: 30312 + 842 = 31154
Step 38: 31154 + 842 = 31996
Step 39: 31996 + 842 = 32838
Step 40: 32838 + 842 = 33680
Step 41: 33680 + 842 = 34522
Step 42: 34522 + 842 = 35364
Step 43: 35364 + 842 = 36206
Step 44: 36206 + 842 = 37048
Step 45: 37048 + 842 = 37890
Step 46: 37890 + 842 = 38732
Step 47: 38732 + 842 = 39574
Step 48: 39574 + 842 = 40416
Step 49: 40416 + 842 = 41258
Step 50: 41258 + 842 = 42100
Step 51: 42100 + 842 = 42942
Step 52: 42942 + 842 = 43784
Step 53: 43784 + 842 = 44626
Step 54: 44626 + 842 = 45468
Step 55: 45468 + 842 = 46310
Step 56: 46310 + 842 = 47152
Step 57: 47152 + 842 = 47994
Step 58: 47994 + 842 = 48836
Step 59: 48836 + 842 = 49678
Step 60: 49678 + 842 = 50520
Step 61: 50520 + 842 = 51362
Step 62: 51362 + 842 = 52204
Step 63: 52204 + 842 = 53046
Step 64: 53046 + 842 = 53888
Step 65: 53888 + 842 = 54730
Step 66: 54730 + 842 = 55572
Step 67: 55572 + 842 = 56414
Step 68: 56414 + 842 = 57256
Step 69: 57256 + 842 = 58098
Step 70: 58098 + 842 = 58940
Step 71: 58940 + 842 = 59782
Step 72: 59782 + 842 = 60624
Step 73: 60624 + 842 = 61466
Step 74: 61466 + 842 = 62308
Step 75: 62308 + 842 = 63150
Step 76: 63150 + 842 = 63992
Step 77: 63992 + 842 = 64834
Step 78: 64834 + 842 = 65676
Step 79: 65676 + 842 = 66518
Step 80: 66518 + 842 = 67360
Step 81: 67360 + 842 = 68202
Step 82: 68202 + 842 = 69044
Step 83: 69044 + 842 = 69886
Step 84: 69886 + 842 = 70728
Step 85: 70728 + 842 = 71570
Step 86: 71570 + 842 = 72412
Step 87: 72412 + 842 = 73254
Step 88: 73254 + 842 = 74096
Step 89: 74096 + 842 = 74938
Step 90: 74938 + 842 = 75780
Step 91: 75780 + 842 = 76622
Step 92: 76622 + 842 = 77464
Step 93: 77464 + 842 = 78306
Step 94: 78306 + 842 = 79148
Step 95: 79148 + 842 = 79990
Step 96: 79990 + 842 = 80832
Step 97: 80832 + 842 = 81674
Step 98: 81674 + 842 = 82516
Step 99: 82516 + 842 = 83358
Step 100: 83358 + 842 = 84200
Step 101: 84200 + 842 = 85042
Step 102: 85042 + 842 = 85884
Step 103: 85884 + 842 = 86726
Step 104: 86726 + 842 = 87568
Step 105: 87568 + 842 = 88410
Step 106: 88410 + 842 = 89252
Step 107: 89252 + 842 = 90094
Step 108: 90094 + 842 = 90936
Step 109: 90936 + 842 = 91778
Step 110: 91778 + 842 = 92620
Step 111: 92620 + 842 = 93462
Step 112: 93462 + 842 = 94304
Step 113: 94304 + 842 = 95146
Step 114: 95146 + 842 = 95988
Step 115: 95988 + 842 = 96830
Step 116: 96830 + 842 = 97672
Step 117: 97672 + 842 = 98514
Step 118: 98514 + 842 = 99356
Step 119: 99356 + 842 = 100198
Step 120: 100198 + 842 = 101040
Step 121: 101040 + 842 = 101882
Step 122: 101882 + 842 = 102724
Step 123: 102724 + 842 = 103566
Step 124: 103566 + 842 = 104408
Step 125: 104408 + 842 = 105250
Step 126: 105250 + 842 = 106092
Step 127: 106092 + 842 = 106934
Step 128: 106934 + 842 = 107776
Step 129: 107776 + 842 = 108618
Step 130: 108618 + 842 = 109460
Step 131: 109460 + 842 = 110302
Step 132: 110302 + 842 = 111144
Step 133: 111144 + 842 = 111986
Step 134: 111986 + 842 = 112828
Step 135: 112828 + 842 = 113670
Step 136: 113670 + 842 = 114512
Step 137: 114512 + 842 = 115354
Step 138: 115354 + 842 = 116196
Step 139: 116196 + 842 = 117038
Step 140: 117038 + 842 = 117880
Step 141: 117880 + 842 = 118722
Step 142: 118722 + 842 = 119564
Step 143: 119564 + 842 = 120406
Step 144: 120406 + 842 = 121248
Step 145: 121248 + 842 = 122090
Step 146: 122090 + 842 = 122932
Step 147: 122932 + 842 = 123774
Step 148: 123774 + 842 = 124616
Step 149: 124616 + 842 = 125458
Step 150: 125458 + 842 = 126300
Step 151: 126300 + 842 = 127142
Step 152: 127142 + 842 = 127984
Step 153: 127984 + 842 = 128826
Step 154: 128826 + 842 = 129668
Step 155: 129668 + 842 = 130510
Step 156: 130510 + 842 = 131352
Step 157: 131352 + 842 = 132194
Step 158: 132194 + 842 = 133036
Step 159: 133036 + 842 = 133878
Step 160: 133878 + 842 = 134720
Step 161: 134720 + 842 = 135562
Step 162: 135562 + 842 = 136404
Step 163: 136404 + 842 = 137246
Step 164: 137246 + 842 = 138088
Step 165: 138088 + 842 = 138930
Step 166: 138930 + 842 = 139772
Step 167: 139772 + 842 = 140614
Step 168: 140614 + 842 = 141456
Step 169: 141456 + 842 = 142298
Step 170: 142298 + 842 = 143140
Step 171: 143140 + 842 = 143982
Step 172: 143982 + 842 = 144824
Step 173: 144824 + 842 = 145666
Step 174: 145666 + 842 = 146508
Step 175: 146508 + 842 = 147350
Step 176: 147350 + 842 = 148192
Step 177: 148192 + 842 = 149034
Step 178: 149034 + 842 = 149876
Step 179: 149876 + 842 = 150718
Step 180: 150718 + 842 = 151560
Step 181: 151560 + 842 = 152402
Step 182: 152402 + 842 = 153244
Step 183: 153244 + 842 = 154086
Step 184: 154086 + 842 = 154928
Step 185: 154928 + 842 = 155770
Step 186: 155770 + 842 = 156612
Step 187: 156612 + 842 = 157454
Step 188: 157454 + 842 = 158296
Step 189: 158296 + 842 = 159138
Step 190: 159138 + 842 = 159980
Step 191: 159980 + 842 = 160822
Step 192: 160822 + 842 = 161664
Step 193: 161664 + 842 = 162506
Step 194: 162506 + 842 = 163348
Step 195: 163348 + 842 = 164190
Step 196: 164190 + 842 = 165032
Step 197: 165032 + 842 = 165874
Step 198: 165874 + 842 = 166716
Step 199: 166716 + 842 = 167558
Step 200: 167558 + 842 = 168400
Step 201: 168400 + 842 = 169242
Step 202: 169242 + 842 = 170084
Step 203: 170084 + 842 = 170926
Step 204: 170926 + 842 = 171768
Step 205: 171768 + 842 = 172610
Step 206: 172610 + 842 = 173452
Step 207: 173452 + 842 = 174294
Step 208: 174294 + 842 = 175136
Step 209: 175136 + 842 = 175978
Step 210: 175978 + 842 = 176820
Step 211: 176820 + 842 = 177662
Step 212: 177662 + 842 = 178504
Step 213: 178504 + 842 = 179346
Step 214: 179346 + 842 = 180188
Step 215: 180188 + 842 = 181030
Step 216: 181030 + 842 = 181872
Step 217: 181872 + 842 = 182714
Step 218: 182714 + 842 = 183556
Step 219: 183556 + 842 = 184398
Step 220: 184398 + 842 = 185240
Step 221: 185240 + 842 = 186082
Step 222: 186082 + 842 = 186924
Step 223: 186924 + 842 = 187766
Step 224: 187766 + 842 = 188608
Step 225: 188608 + 842 = 189450
Step 226: 189450 + 842 = 190292
Step 227: 190292 + 842 = 191134
Step 228: 191134 + 842 = 191976
Step 229: 191976 + 842 = 192818
Step 230: 192818 + 842 = 193660
Step 231: 193660 + 842 = 194502
Step 232: 194502 + 842 = 195344
Step 233: 195344 + 842 = 196186
Step 234: 196186 + 842 = 197028
Step 235: 197028 + 842 = 197870
Step 236: 197870 + 842 = 198712
Step 237: 198712 + 842 = 199554
Step 238: 199554 + 842 = 200396
Step 239: 200396 + 842 = 201238
Step 240: 201238 + 842 = 202080
Step 241: 202080 + 842 = 202922
Step 242: 202922 + 842 = 203764
Step 243: 203764 + 842 = 204606
Step 244: 204606 + 842 = 205448
Step 245: 205448 + 842 = 206290
Step 246: 206290 + 842 = 207132
Step 247: 207132 + 842 = 207974
Step 248: 207974 + 842 = 208816
Step 249: 208816 + 842 = 209658
Step 250: 209658 + 842 = 210500
Step 251: 210500 + 842 = 211342
Step 252: 211342 + 842 = 212184
Step 253: 212184 + 842 = 213026
Step 254: 213026 + 842 = 213868
Step 255: 213868 + 842 = 214710
Step 256: 214710 + 842 = 215552
Step 257: 215552 + 842 = 216394
Step 258: 216394 + 842 = 217236
Step 259: 217236 + 842 = 218078
Step 260: 218078 + 842 = 218920
Step 261: 218920 + 842 = 219762
Step 262: 219762 + 842 = 220604
Step 263: 220604 + 842 = 221446
Step 264: 221446 + 842 = 222288
Step 265: 222288 + 842 = 223130
Step 266: 223130 + 842 = 223972
Step 267: 223972 + 842 = 224814
Step 268: 224814 + 842 = 225656
Step 269: 225656 + 842 = 226498
Step 270: 226498 + 842 = 227340
Step 271: 227340 + 842 = 228182
Step 272: 228182 + 842 = 229024
Step 273: 229024 + 842 = 229866
Step 274: 229866 + 842 = 230708
Step 275: 230708 + 842 = 231550
Step 276: 231550 + 842 = 232392
Step 277: 232392 + 842 = 233234
Step 278: 233234 + 842 = 234076
Step 279: 234076 + 842 = 234918
Step 280: 234918 + 842 = 235760
Step 281: 235760 + 842 = 236602
Step 282: 236602 + 842 = 237444
Step 283: 237444 + 842 = 238286
Step 284: 238286 + 842 = 239128
Step 285: 239128 + 842 = 239970
Step 286: 239970 + 842 = 240812
Step 287: 240812 + 842 = 241654
Step 288: 241654 + 842 = 242496
Step 289: 242496 + 842 = 243338
Step 290: 243338 + 842 = 244180
Step 291: 244180 + 842 = 245022
Step 292: 245022 + 842 = 245864
Step 293: 245864 + 842 = 246706
Step 294: 246706 + 842 = 247548
Step 295: 247548 + 842 = 248390
Step 296: 248390 + 842 = 249232
Step 297: 249232 + 842 = 250074
Step 298: 250074 + 842 = 250916
Step 299: 250916 + 842 = 251758
Step 300: 251758 + 842 = 252600
Step 301: 252600 + 842 = 253442
Step 302: 253442 + 842 = 254284
Step 303: 254284 + 842 = 255126
Step 304: 255126 + 842 = 255968
Step 305: 255968 + 842 = 256810
Step 306: 256810 + 842 = 257652
Step 307: 257652 + 842 = 258494
Step 308: 258494 + 842 = 259336
Step 309: 259336 + 842 = 260178
Step 310: 260178 + 842 = 261020
Step 311: 261020 + 842 = 261862
Step 312: 261862 + 842 = 262704
Step 313: 262704 + 842 = 263546
Step 314: 263546 + 842 = 264388
Step 315: 264388 + 842 = 265230
Step 316: 265230 + 842 = 266072
Step 317: 266072 + 842 = 266914
Step 318: 266914 + 842 = 267756
Step 319: 267756 + 842 = 268598
Step 320: 268598 + 842 = 269440
Step 321: 269440 + 842 = 270282
Step 322: 270282 + 842 = 271124
Step 323: 271124 + 842 = 271966
Step 324: 271966 + 842 = 272808
Step 325: 272808 + 842 = 273650
Step 326: 273650 + 842 = 274492
Step 327: 274492 + 842 = 275334
Step 328: 275334 + 842 = 276176
Step 329: 276176 + 842 = 277018
Step 330: 277018 + 842 = 277860
Step 331: 277860 + 842 = 278702
Step 332: 278702 + 842 = 279544
Step 333: 279544 + 842 = 280386
Step 334: 280386 + 842 = 281228
Step 335: 281228 + 842 = 282070
Step 336: 282070 + 842 = 282912
Step 337: 282912 + 842 = 283754
Step 338: 283754 + 842 = 284596
Step 339: 284596 + 842 = 285438
Step 340: 285438 + 842 = 286280
Step 341: 286280 + 842 = 287122
Step 342: 287122 + 842 = 287964
Step 343: 287964 + 842 = 288806
Step 344: 288806 + 842 = 289648
Step 345: 289648 + 842 = 290490
Step 346: 290490 + 842 = 291332
Step 347: 291332 + 842 = 292174
Step 348: 292174 + 842 = 293016
Step 349: 293016 + 842 = 293858
Step 350: 293858 + 842 = 294700
Step 351: 294700 + 842 = 295542
Step 352: 295542 + 842 = 296384
Step 353: 296384 + 842 = 297226
Step 354: 297226 + 842 = 298068
Step 355: 298068 + 842 = 298910
Step 356: 298910 + 842 = 299752
Step 357: 299752 + 842 = 300594
Step 358: 300594 + 842 = 301436
Step 359: 301436 + 842 = 302278
Step 360: 302278 + 842 = 303120
Step 361: 303120 + 842 = 303962
Step 362: 303962 + 842 = 304804
Step 363: 304804 + 842 = 305646
Step 364: 305646 + 842 = 306488
Step 365: 306488 + 842 = 307330
Step 366: 307330 + 842 = 308172
Step 367: 308172 + 842 = 309014
Step 368: 309014 + 842 = 309856
Step 369: 309856 + 842 = 310698
Step 370: 310698 + 842 = 311540
Step 371: 311540 + 842 = 312382
Step 372: 312382 + 842 = 313224
Step 373: 313224 + 842 = 314066
Step 374: 314066 + 842 = 314908
Step 375: 314908 + 842 = 315750
Step 376: 315750 + 842 = 316592
Step 377: 316592 + 842 = 317434
Step 378: 317434 + 842 = 318276
Step 379: 318276 + 842 = 319118
Step 380: 319118 + 842 = 319960
Step 381: 319960 + 842 = 320802
Step 382: 320802 + 842 = 321644
Step 383: 321644 + 842 = 322486
Step 384: 322486 + 842 = 323328
Step 385: 323328 + 842 = 324170
Step 386: 324170 + 842 = 325012
Step 387: 325012 + 842 = 325854
Step 388: 325854 + 842 = 326696
Step 389: 326696 + 842 = 327538
Step 390: 327538 + 842 = 328380
Step 391: 328380 + 842 = 329222
Step 392: 329222 + 842 = 330064
Step 393: 330064 + 842 = 330906
Step 394: 330906 + 842 = 331748

So, 842*394 = 331748