Let's roll up our sleeves and solve this. We have 639 and we're going to multiply it by 266, essentially adding 639 to itself 266 times.
Step 1: 0 + 639 = 639
Step 2: 639 + 639 = 1278
Step 3: 1278 + 639 = 1917
Step 4: 1917 + 639 = 2556
Step 5: 2556 + 639 = 3195
Step 6: 3195 + 639 = 3834
Step 7: 3834 + 639 = 4473
Step 8: 4473 + 639 = 5112
Step 9: 5112 + 639 = 5751
Step 10: 5751 + 639 = 6390
Step 11: 6390 + 639 = 7029
Step 12: 7029 + 639 = 7668
Step 13: 7668 + 639 = 8307
Step 14: 8307 + 639 = 8946
Step 15: 8946 + 639 = 9585
Step 16: 9585 + 639 = 10224
Step 17: 10224 + 639 = 10863
Step 18: 10863 + 639 = 11502
Step 19: 11502 + 639 = 12141
Step 20: 12141 + 639 = 12780
Step 21: 12780 + 639 = 13419
Step 22: 13419 + 639 = 14058
Step 23: 14058 + 639 = 14697
Step 24: 14697 + 639 = 15336
Step 25: 15336 + 639 = 15975
Step 26: 15975 + 639 = 16614
Step 27: 16614 + 639 = 17253
Step 28: 17253 + 639 = 17892
Step 29: 17892 + 639 = 18531
Step 30: 18531 + 639 = 19170
Step 31: 19170 + 639 = 19809
Step 32: 19809 + 639 = 20448
Step 33: 20448 + 639 = 21087
Step 34: 21087 + 639 = 21726
Step 35: 21726 + 639 = 22365
Step 36: 22365 + 639 = 23004
Step 37: 23004 + 639 = 23643
Step 38: 23643 + 639 = 24282
Step 39: 24282 + 639 = 24921
Step 40: 24921 + 639 = 25560
Step 41: 25560 + 639 = 26199
Step 42: 26199 + 639 = 26838
Step 43: 26838 + 639 = 27477
Step 44: 27477 + 639 = 28116
Step 45: 28116 + 639 = 28755
Step 46: 28755 + 639 = 29394
Step 47: 29394 + 639 = 30033
Step 48: 30033 + 639 = 30672
Step 49: 30672 + 639 = 31311
Step 50: 31311 + 639 = 31950
Step 51: 31950 + 639 = 32589
Step 52: 32589 + 639 = 33228
Step 53: 33228 + 639 = 33867
Step 54: 33867 + 639 = 34506
Step 55: 34506 + 639 = 35145
Step 56: 35145 + 639 = 35784
Step 57: 35784 + 639 = 36423
Step 58: 36423 + 639 = 37062
Step 59: 37062 + 639 = 37701
Step 60: 37701 + 639 = 38340
Step 61: 38340 + 639 = 38979
Step 62: 38979 + 639 = 39618
Step 63: 39618 + 639 = 40257
Step 64: 40257 + 639 = 40896
Step 65: 40896 + 639 = 41535
Step 66: 41535 + 639 = 42174
Step 67: 42174 + 639 = 42813
Step 68: 42813 + 639 = 43452
Step 69: 43452 + 639 = 44091
Step 70: 44091 + 639 = 44730
Step 71: 44730 + 639 = 45369
Step 72: 45369 + 639 = 46008
Step 73: 46008 + 639 = 46647
Step 74: 46647 + 639 = 47286
Step 75: 47286 + 639 = 47925
Step 76: 47925 + 639 = 48564
Step 77: 48564 + 639 = 49203
Step 78: 49203 + 639 = 49842
Step 79: 49842 + 639 = 50481
Step 80: 50481 + 639 = 51120
Step 81: 51120 + 639 = 51759
Step 82: 51759 + 639 = 52398
Step 83: 52398 + 639 = 53037
Step 84: 53037 + 639 = 53676
Step 85: 53676 + 639 = 54315
Step 86: 54315 + 639 = 54954
Step 87: 54954 + 639 = 55593
Step 88: 55593 + 639 = 56232
Step 89: 56232 + 639 = 56871
Step 90: 56871 + 639 = 57510
Step 91: 57510 + 639 = 58149
Step 92: 58149 + 639 = 58788
Step 93: 58788 + 639 = 59427
Step 94: 59427 + 639 = 60066
Step 95: 60066 + 639 = 60705
Step 96: 60705 + 639 = 61344
Step 97: 61344 + 639 = 61983
Step 98: 61983 + 639 = 62622
Step 99: 62622 + 639 = 63261
Step 100: 63261 + 639 = 63900
Step 101: 63900 + 639 = 64539
Step 102: 64539 + 639 = 65178
Step 103: 65178 + 639 = 65817
Step 104: 65817 + 639 = 66456
Step 105: 66456 + 639 = 67095
Step 106: 67095 + 639 = 67734
Step 107: 67734 + 639 = 68373
Step 108: 68373 + 639 = 69012
Step 109: 69012 + 639 = 69651
Step 110: 69651 + 639 = 70290
Step 111: 70290 + 639 = 70929
Step 112: 70929 + 639 = 71568
Step 113: 71568 + 639 = 72207
Step 114: 72207 + 639 = 72846
Step 115: 72846 + 639 = 73485
Step 116: 73485 + 639 = 74124
Step 117: 74124 + 639 = 74763
Step 118: 74763 + 639 = 75402
Step 119: 75402 + 639 = 76041
Step 120: 76041 + 639 = 76680
Step 121: 76680 + 639 = 77319
Step 122: 77319 + 639 = 77958
Step 123: 77958 + 639 = 78597
Step 124: 78597 + 639 = 79236
Step 125: 79236 + 639 = 79875
Step 126: 79875 + 639 = 80514
Step 127: 80514 + 639 = 81153
Step 128: 81153 + 639 = 81792
Step 129: 81792 + 639 = 82431
Step 130: 82431 + 639 = 83070
Step 131: 83070 + 639 = 83709
Step 132: 83709 + 639 = 84348
Step 133: 84348 + 639 = 84987
Step 134: 84987 + 639 = 85626
Step 135: 85626 + 639 = 86265
Step 136: 86265 + 639 = 86904
Step 137: 86904 + 639 = 87543
Step 138: 87543 + 639 = 88182
Step 139: 88182 + 639 = 88821
Step 140: 88821 + 639 = 89460
Step 141: 89460 + 639 = 90099
Step 142: 90099 + 639 = 90738
Step 143: 90738 + 639 = 91377
Step 144: 91377 + 639 = 92016
Step 145: 92016 + 639 = 92655
Step 146: 92655 + 639 = 93294
Step 147: 93294 + 639 = 93933
Step 148: 93933 + 639 = 94572
Step 149: 94572 + 639 = 95211
Step 150: 95211 + 639 = 95850
Step 151: 95850 + 639 = 96489
Step 152: 96489 + 639 = 97128
Step 153: 97128 + 639 = 97767
Step 154: 97767 + 639 = 98406
Step 155: 98406 + 639 = 99045
Step 156: 99045 + 639 = 99684
Step 157: 99684 + 639 = 100323
Step 158: 100323 + 639 = 100962
Step 159: 100962 + 639 = 101601
Step 160: 101601 + 639 = 102240
Step 161: 102240 + 639 = 102879
Step 162: 102879 + 639 = 103518
Step 163: 103518 + 639 = 104157
Step 164: 104157 + 639 = 104796
Step 165: 104796 + 639 = 105435
Step 166: 105435 + 639 = 106074
Step 167: 106074 + 639 = 106713
Step 168: 106713 + 639 = 107352
Step 169: 107352 + 639 = 107991
Step 170: 107991 + 639 = 108630
Step 171: 108630 + 639 = 109269
Step 172: 109269 + 639 = 109908
Step 173: 109908 + 639 = 110547
Step 174: 110547 + 639 = 111186
Step 175: 111186 + 639 = 111825
Step 176: 111825 + 639 = 112464
Step 177: 112464 + 639 = 113103
Step 178: 113103 + 639 = 113742
Step 179: 113742 + 639 = 114381
Step 180: 114381 + 639 = 115020
Step 181: 115020 + 639 = 115659
Step 182: 115659 + 639 = 116298
Step 183: 116298 + 639 = 116937
Step 184: 116937 + 639 = 117576
Step 185: 117576 + 639 = 118215
Step 186: 118215 + 639 = 118854
Step 187: 118854 + 639 = 119493
Step 188: 119493 + 639 = 120132
Step 189: 120132 + 639 = 120771
Step 190: 120771 + 639 = 121410
Step 191: 121410 + 639 = 122049
Step 192: 122049 + 639 = 122688
Step 193: 122688 + 639 = 123327
Step 194: 123327 + 639 = 123966
Step 195: 123966 + 639 = 124605
Step 196: 124605 + 639 = 125244
Step 197: 125244 + 639 = 125883
Step 198: 125883 + 639 = 126522
Step 199: 126522 + 639 = 127161
Step 200: 127161 + 639 = 127800
Step 201: 127800 + 639 = 128439
Step 202: 128439 + 639 = 129078
Step 203: 129078 + 639 = 129717
Step 204: 129717 + 639 = 130356
Step 205: 130356 + 639 = 130995
Step 206: 130995 + 639 = 131634
Step 207: 131634 + 639 = 132273
Step 208: 132273 + 639 = 132912
Step 209: 132912 + 639 = 133551
Step 210: 133551 + 639 = 134190
Step 211: 134190 + 639 = 134829
Step 212: 134829 + 639 = 135468
Step 213: 135468 + 639 = 136107
Step 214: 136107 + 639 = 136746
Step 215: 136746 + 639 = 137385
Step 216: 137385 + 639 = 138024
Step 217: 138024 + 639 = 138663
Step 218: 138663 + 639 = 139302
Step 219: 139302 + 639 = 139941
Step 220: 139941 + 639 = 140580
Step 221: 140580 + 639 = 141219
Step 222: 141219 + 639 = 141858
Step 223: 141858 + 639 = 142497
Step 224: 142497 + 639 = 143136
Step 225: 143136 + 639 = 143775
Step 226: 143775 + 639 = 144414
Step 227: 144414 + 639 = 145053
Step 228: 145053 + 639 = 145692
Step 229: 145692 + 639 = 146331
Step 230: 146331 + 639 = 146970
Step 231: 146970 + 639 = 147609
Step 232: 147609 + 639 = 148248
Step 233: 148248 + 639 = 148887
Step 234: 148887 + 639 = 149526
Step 235: 149526 + 639 = 150165
Step 236: 150165 + 639 = 150804
Step 237: 150804 + 639 = 151443
Step 238: 151443 + 639 = 152082
Step 239: 152082 + 639 = 152721
Step 240: 152721 + 639 = 153360
Step 241: 153360 + 639 = 153999
Step 242: 153999 + 639 = 154638
Step 243: 154638 + 639 = 155277
Step 244: 155277 + 639 = 155916
Step 245: 155916 + 639 = 156555
Step 246: 156555 + 639 = 157194
Step 247: 157194 + 639 = 157833
Step 248: 157833 + 639 = 158472
Step 249: 158472 + 639 = 159111
Step 250: 159111 + 639 = 159750
Step 251: 159750 + 639 = 160389
Step 252: 160389 + 639 = 161028
Step 253: 161028 + 639 = 161667
Step 254: 161667 + 639 = 162306
Step 255: 162306 + 639 = 162945
Step 256: 162945 + 639 = 163584
Step 257: 163584 + 639 = 164223
Step 258: 164223 + 639 = 164862
Step 259: 164862 + 639 = 165501
Step 260: 165501 + 639 = 166140
Step 261: 166140 + 639 = 166779
Step 262: 166779 + 639 = 167418
Step 263: 167418 + 639 = 168057
Step 264: 168057 + 639 = 168696
Step 265: 168696 + 639 = 169335
Step 266: 169335 + 639 = 169974

So, 639*266 = 169974