Написал программку (возможно, с ошибками).
Нашла для 6
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6 * 1273 = 7638 6 * 4859 = 29154
6 * 1273 = 7638 6 * 8549 = 51294
6 * 1273 = 7638 6 * 9854 = 59124
6 * 1523 = 9138 6 * 8794 = 52764
6 * 1543 = 9258 6 * 2789 = 16734
6 * 1594 = 9564 6 * 2873 = 17238
Нашла для 3
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3 * 1247 = 3741 3 * 8965 = 26895
3 * 1247 = 3741 3 * 9856 = 29568
3 * 1256 = 3768 3 * 8497 = 25491
3 * 1256 = 3768 3 * 9847 = 29541
3 * 1265 = 3795 3 * 8947 = 26841
3 * 1265 = 3795 3 * 9487 = 28461
3 * 1275 = 3825 3 * 6489 = 19467
3 * 1289 = 3867 3 * 4765 = 14295
3 * 1289 = 3867 3 * 6475 = 19425
3 * 1457 = 4371 3 * 9862 = 29586
3 * 1462 = 4386 3 * 8597 = 25791
3 * 1462 = 4386 3 * 9857 = 29571
3 * 1465 = 4395 3 * 7289 = 21867
3 * 1465 = 4395 3 * 8729 = 26187
3 * 1465 = 4395 3 * 8927 = 26781
3 * 1465 = 4395 3 * 9287 = 27861
3 * 1572 = 4716 3 * 9846 = 29538
3 * 1597 = 4791 3 * 8462 = 25386
3 * 1645 = 4935 3 * 7289 = 21867
3 * 1645 = 4935 3 * 8729 = 26187
3 * 1645 = 4935 3 * 8927 = 26781
3 * 1645 = 4935 3 * 9287 = 27861
3 * 1746 = 5238 3 * 5982 = 17946
3 * 1762 = 5286 3 * 4598 = 13794
3 * 1782 = 5346 3 * 5964 = 17892
3 * 1782 = 5346 3 * 6594 = 19782
3 * 1794 = 5382 3 * 6582 = 19746
3 * 1798 = 5394 3 * 4256 = 12768
3 * 1798 = 5394 3 * 5426 = 16278
3 * 1798 = 5394 3 * 5624 = 16872
3 * 1798 = 5394 3 * 6254 = 18762
3 * 1942 = 5826 3 * 6578 = 19734
3 * 1964 = 5892 3 * 5782 = 17346
3 * 1976 = 5928 3 * 4582 = 13746
3 * 1978 = 5934 3 * 4256 = 12768
3 * 1978 = 5934 3 * 5426 = 16278
3 * 1978 = 5934 3 * 5624 = 16872
3 * 1978 = 5934 3 * 6254 = 18762
3 * 1982 = 5946 3 * 4576 = 13728
3 * 1982 = 5946 3 * 5746 = 17238
3 * 2146 = 6438 3 * 8597 = 25791
3 * 2146 = 6438 3 * 9857 = 29571
3 * 2157 = 6471 3 * 9846 = 29538
3 * 2176 = 6528 3 * 4598 = 13794
3 * 2178 = 6534 3 * 5964 = 17892
3 * 2178 = 6534 3 * 6594 = 19782
3 * 2194 = 6582 3 * 6578 = 19734
3 * 2198 = 6594 3 * 4576 = 13728
3 * 2198 = 6594 3 * 5746 = 17238
3 * 2456 = 7368 3 * 7198 = 21594
3 * 2456 = 7368 3 * 8197 = 24591
3 * 2456 = 7368 3 * 9718 = 29154
3 * 2456 = 7368 3 * 9817 = 29451
3 * 2471 = 7413 3 * 8965 = 26895
3 * 2471 = 7413 3 * 9856 = 29568
3 * 2487 = 7461 3 * 9651 = 28953
3 * 2497 = 7491 3 * 8561 = 25683
3 * 2546 = 7638 3 * 7198 = 21594
3 * 2546 = 7638 3 * 8197 = 24591
3 * 2546 = 7638 3 * 9718 = 29154
3 * 2546 = 7638 3 * 9817 = 29451
3 * 2547 = 7641 3 * 9861 = 29583
3 * 2561 = 7683 3 * 8497 = 25491
3 * 2561 = 7683 3 * 9847 = 29541
3 * 2647 = 7941 3 * 8951 = 26853
3 * 2651 = 7953 3 * 8947 = 26841
3 * 2651 = 7953 3 * 9487 = 28461
3 * 2751 = 8253 3 * 6489 = 19467
3 * 2765 = 8295 3 * 4891 = 14673
3 * 2789 = 8367 3 * 4165 = 12495
3 * 2789 = 8367 3 * 5164 = 15492
3 * 2789 = 8367 3 * 6415 = 19245
3 * 2789 = 8367 3 * 6514 = 19542
3 * 2875 = 8625 3 * 6491 = 19473
3 * 2879 = 8637 3 * 4165 = 12495
3 * 2879 = 8637 3 * 5164 = 15492
3 * 2879 = 8637 3 * 6415 = 19245
3 * 2879 = 8637 3 * 6514 = 19542
3 * 2891 = 8673 3 * 4765 = 14295
3 * 2891 = 8673 3 * 6475 = 19425
Очевидно, что для 0, 1 и 5 таких не будет. А для 2,4,7,8,9 программа не нашла.