OK, let's work through this together. We're starting with 901 and we're going to multiply it by 279, which means we add 901 to itself 279 times.
Step 1: 0 + 901 = 901
Step 2: 901 + 901 = 1802
Step 3: 1802 + 901 = 2703
Step 4: 2703 + 901 = 3604
Step 5: 3604 + 901 = 4505
Step 6: 4505 + 901 = 5406
Step 7: 5406 + 901 = 6307
Step 8: 6307 + 901 = 7208
Step 9: 7208 + 901 = 8109
Step 10: 8109 + 901 = 9010
Step 11: 9010 + 901 = 9911
Step 12: 9911 + 901 = 10812
Step 13: 10812 + 901 = 11713
Step 14: 11713 + 901 = 12614
Step 15: 12614 + 901 = 13515
Step 16: 13515 + 901 = 14416
Step 17: 14416 + 901 = 15317
Step 18: 15317 + 901 = 16218
Step 19: 16218 + 901 = 17119
Step 20: 17119 + 901 = 18020
Step 21: 18020 + 901 = 18921
Step 22: 18921 + 901 = 19822
Step 23: 19822 + 901 = 20723
Step 24: 20723 + 901 = 21624
Step 25: 21624 + 901 = 22525
Step 26: 22525 + 901 = 23426
Step 27: 23426 + 901 = 24327
Step 28: 24327 + 901 = 25228
Step 29: 25228 + 901 = 26129
Step 30: 26129 + 901 = 27030
Step 31: 27030 + 901 = 27931
Step 32: 27931 + 901 = 28832
Step 33: 28832 + 901 = 29733
Step 34: 29733 + 901 = 30634
Step 35: 30634 + 901 = 31535
Step 36: 31535 + 901 = 32436
Step 37: 32436 + 901 = 33337
Step 38: 33337 + 901 = 34238
Step 39: 34238 + 901 = 35139
Step 40: 35139 + 901 = 36040
Step 41: 36040 + 901 = 36941
Step 42: 36941 + 901 = 37842
Step 43: 37842 + 901 = 38743
Step 44: 38743 + 901 = 39644
Step 45: 39644 + 901 = 40545
Step 46: 40545 + 901 = 41446
Step 47: 41446 + 901 = 42347
Step 48: 42347 + 901 = 43248
Step 49: 43248 + 901 = 44149
Step 50: 44149 + 901 = 45050
Step 51: 45050 + 901 = 45951
Step 52: 45951 + 901 = 46852
Step 53: 46852 + 901 = 47753
Step 54: 47753 + 901 = 48654
Step 55: 48654 + 901 = 49555
Step 56: 49555 + 901 = 50456
Step 57: 50456 + 901 = 51357
Step 58: 51357 + 901 = 52258
Step 59: 52258 + 901 = 53159
Step 60: 53159 + 901 = 54060
Step 61: 54060 + 901 = 54961
Step 62: 54961 + 901 = 55862
Step 63: 55862 + 901 = 56763
Step 64: 56763 + 901 = 57664
Step 65: 57664 + 901 = 58565
Step 66: 58565 + 901 = 59466
Step 67: 59466 + 901 = 60367
Step 68: 60367 + 901 = 61268
Step 69: 61268 + 901 = 62169
Step 70: 62169 + 901 = 63070
Step 71: 63070 + 901 = 63971
Step 72: 63971 + 901 = 64872
Step 73: 64872 + 901 = 65773
Step 74: 65773 + 901 = 66674
Step 75: 66674 + 901 = 67575
Step 76: 67575 + 901 = 68476
Step 77: 68476 + 901 = 69377
Step 78: 69377 + 901 = 70278
Step 79: 70278 + 901 = 71179
Step 80: 71179 + 901 = 72080
Step 81: 72080 + 901 = 72981
Step 82: 72981 + 901 = 73882
Step 83: 73882 + 901 = 74783
Step 84: 74783 + 901 = 75684
Step 85: 75684 + 901 = 76585
Step 86: 76585 + 901 = 77486
Step 87: 77486 + 901 = 78387
Step 88: 78387 + 901 = 79288
Step 89: 79288 + 901 = 80189
Step 90: 80189 + 901 = 81090
Step 91: 81090 + 901 = 81991
Step 92: 81991 + 901 = 82892
Step 93: 82892 + 901 = 83793
Step 94: 83793 + 901 = 84694
Step 95: 84694 + 901 = 85595
Step 96: 85595 + 901 = 86496
Step 97: 86496 + 901 = 87397
Step 98: 87397 + 901 = 88298
Step 99: 88298 + 901 = 89199
Step 100: 89199 + 901 = 90100
Step 101: 90100 + 901 = 91001
Step 102: 91001 + 901 = 91902
Step 103: 91902 + 901 = 92803
Step 104: 92803 + 901 = 93704
Step 105: 93704 + 901 = 94605
Step 106: 94605 + 901 = 95506
Step 107: 95506 + 901 = 96407
Step 108: 96407 + 901 = 97308
Step 109: 97308 + 901 = 98209
Step 110: 98209 + 901 = 99110
Step 111: 99110 + 901 = 100011
Step 112: 100011 + 901 = 100912
Step 113: 100912 + 901 = 101813
Step 114: 101813 + 901 = 102714
Step 115: 102714 + 901 = 103615
Step 116: 103615 + 901 = 104516
Step 117: 104516 + 901 = 105417
Step 118: 105417 + 901 = 106318
Step 119: 106318 + 901 = 107219
Step 120: 107219 + 901 = 108120
Step 121: 108120 + 901 = 109021
Step 122: 109021 + 901 = 109922
Step 123: 109922 + 901 = 110823
Step 124: 110823 + 901 = 111724
Step 125: 111724 + 901 = 112625
Step 126: 112625 + 901 = 113526
Step 127: 113526 + 901 = 114427
Step 128: 114427 + 901 = 115328
Step 129: 115328 + 901 = 116229
Step 130: 116229 + 901 = 117130
Step 131: 117130 + 901 = 118031
Step 132: 118031 + 901 = 118932
Step 133: 118932 + 901 = 119833
Step 134: 119833 + 901 = 120734
Step 135: 120734 + 901 = 121635
Step 136: 121635 + 901 = 122536
Step 137: 122536 + 901 = 123437
Step 138: 123437 + 901 = 124338
Step 139: 124338 + 901 = 125239
Step 140: 125239 + 901 = 126140
Step 141: 126140 + 901 = 127041
Step 142: 127041 + 901 = 127942
Step 143: 127942 + 901 = 128843
Step 144: 128843 + 901 = 129744
Step 145: 129744 + 901 = 130645
Step 146: 130645 + 901 = 131546
Step 147: 131546 + 901 = 132447
Step 148: 132447 + 901 = 133348
Step 149: 133348 + 901 = 134249
Step 150: 134249 + 901 = 135150
Step 151: 135150 + 901 = 136051
Step 152: 136051 + 901 = 136952
Step 153: 136952 + 901 = 137853
Step 154: 137853 + 901 = 138754
Step 155: 138754 + 901 = 139655
Step 156: 139655 + 901 = 140556
Step 157: 140556 + 901 = 141457
Step 158: 141457 + 901 = 142358
Step 159: 142358 + 901 = 143259
Step 160: 143259 + 901 = 144160
Step 161: 144160 + 901 = 145061
Step 162: 145061 + 901 = 145962
Step 163: 145962 + 901 = 146863
Step 164: 146863 + 901 = 147764
Step 165: 147764 + 901 = 148665
Step 166: 148665 + 901 = 149566
Step 167: 149566 + 901 = 150467
Step 168: 150467 + 901 = 151368
Step 169: 151368 + 901 = 152269
Step 170: 152269 + 901 = 153170
Step 171: 153170 + 901 = 154071
Step 172: 154071 + 901 = 154972
Step 173: 154972 + 901 = 155873
Step 174: 155873 + 901 = 156774
Step 175: 156774 + 901 = 157675
Step 176: 157675 + 901 = 158576
Step 177: 158576 + 901 = 159477
Step 178: 159477 + 901 = 160378
Step 179: 160378 + 901 = 161279
Step 180: 161279 + 901 = 162180
Step 181: 162180 + 901 = 163081
Step 182: 163081 + 901 = 163982
Step 183: 163982 + 901 = 164883
Step 184: 164883 + 901 = 165784
Step 185: 165784 + 901 = 166685
Step 186: 166685 + 901 = 167586
Step 187: 167586 + 901 = 168487
Step 188: 168487 + 901 = 169388
Step 189: 169388 + 901 = 170289
Step 190: 170289 + 901 = 171190
Step 191: 171190 + 901 = 172091
Step 192: 172091 + 901 = 172992
Step 193: 172992 + 901 = 173893
Step 194: 173893 + 901 = 174794
Step 195: 174794 + 901 = 175695
Step 196: 175695 + 901 = 176596
Step 197: 176596 + 901 = 177497
Step 198: 177497 + 901 = 178398
Step 199: 178398 + 901 = 179299
Step 200: 179299 + 901 = 180200
Step 201: 180200 + 901 = 181101
Step 202: 181101 + 901 = 182002
Step 203: 182002 + 901 = 182903
Step 204: 182903 + 901 = 183804
Step 205: 183804 + 901 = 184705
Step 206: 184705 + 901 = 185606
Step 207: 185606 + 901 = 186507
Step 208: 186507 + 901 = 187408
Step 209: 187408 + 901 = 188309
Step 210: 188309 + 901 = 189210
Step 211: 189210 + 901 = 190111
Step 212: 190111 + 901 = 191012
Step 213: 191012 + 901 = 191913
Step 214: 191913 + 901 = 192814
Step 215: 192814 + 901 = 193715
Step 216: 193715 + 901 = 194616
Step 217: 194616 + 901 = 195517
Step 218: 195517 + 901 = 196418
Step 219: 196418 + 901 = 197319
Step 220: 197319 + 901 = 198220
Step 221: 198220 + 901 = 199121
Step 222: 199121 + 901 = 200022
Step 223: 200022 + 901 = 200923
Step 224: 200923 + 901 = 201824
Step 225: 201824 + 901 = 202725
Step 226: 202725 + 901 = 203626
Step 227: 203626 + 901 = 204527
Step 228: 204527 + 901 = 205428
Step 229: 205428 + 901 = 206329
Step 230: 206329 + 901 = 207230
Step 231: 207230 + 901 = 208131
Step 232: 208131 + 901 = 209032
Step 233: 209032 + 901 = 209933
Step 234: 209933 + 901 = 210834
Step 235: 210834 + 901 = 211735
Step 236: 211735 + 901 = 212636
Step 237: 212636 + 901 = 213537
Step 238: 213537 + 901 = 214438
Step 239: 214438 + 901 = 215339
Step 240: 215339 + 901 = 216240
Step 241: 216240 + 901 = 217141
Step 242: 217141 + 901 = 218042
Step 243: 218042 + 901 = 218943
Step 244: 218943 + 901 = 219844
Step 245: 219844 + 901 = 220745
Step 246: 220745 + 901 = 221646
Step 247: 221646 + 901 = 222547
Step 248: 222547 + 901 = 223448
Step 249: 223448 + 901 = 224349
Step 250: 224349 + 901 = 225250
Step 251: 225250 + 901 = 226151
Step 252: 226151 + 901 = 227052
Step 253: 227052 + 901 = 227953
Step 254: 227953 + 901 = 228854
Step 255: 228854 + 901 = 229755
Step 256: 229755 + 901 = 230656
Step 257: 230656 + 901 = 231557
Step 258: 231557 + 901 = 232458
Step 259: 232458 + 901 = 233359
Step 260: 233359 + 901 = 234260
Step 261: 234260 + 901 = 235161
Step 262: 235161 + 901 = 236062
Step 263: 236062 + 901 = 236963
Step 264: 236963 + 901 = 237864
Step 265: 237864 + 901 = 238765
Step 266: 238765 + 901 = 239666
Step 267: 239666 + 901 = 240567
Step 268: 240567 + 901 = 241468
Step 269: 241468 + 901 = 242369
Step 270: 242369 + 901 = 243270
Step 271: 243270 + 901 = 244171
Step 272: 244171 + 901 = 245072
Step 273: 245072 + 901 = 245973
Step 274: 245973 + 901 = 246874
Step 275: 246874 + 901 = 247775
Step 276: 247775 + 901 = 248676
Step 277: 248676 + 901 = 249577
Step 278: 249577 + 901 = 250478
Step 279: 250478 + 901 = 251379

So, 901*279 = 251379