这里有个问题,就是数字的首位数可不可以是0?虽然说首位的0常常是省略掉的,但是写的话也不能算错,所以还是你自己来判断吧。结论是：如果首位不允许为0,那么共有60种,如果首位可以为0,那么共有228种。
所有解都列在下面：1 42 695 = 07381 43 685 = 07291 45 683 = 07291 45 692 = 07381 52 793 = 08461 53 792 = 08461 72 386 = 04591 72 395 = 04681 75 392 = 04681 76 382 = 04591 82 376 = 04591 82 493 = 05761 83 492 = 05761 83 645 = 07291 85 643 = 07291 86 372 = 04591 92 375 = 04681 92 483 = 05761 92 645 = 07381 92 753 = 08461 93 482 = 05761 93 752 = 08461 95 372 = 04681 95 642 = 07382 41 695 = 07382 45 691 = 07382 46 987 = 10352 47 986 = 10352 51 793 = 08462 53 764 = 08192 53 791 = 08462 54 763 = 08192 63 754 = 08192 64 753 = 08192 64 987 = 10532 67 984 = 10532 71 386 = 04592 71 395 = 04682 75 391 = 04682 76 381 = 04592 81 376 = 04592 81 493 = 05762 83 491 = 05762 84 967 = 10532 86 371 = 04592 86 947 = 10352 87 946 = 10352 87 964 = 10532 91 375 = 04682 91 483 = 05762 91 645 = 07382 91 753 = 08462 93 481 = 05762 93 751 = 08462 95 371 = 04682 95 641 = 07383 41 685 = 07293 45 681 = 07293 45 978 = 10263 48 975 = 10263 51 792 = 08463 52 764 = 08193 52 791 = 08463 54 762 = 08193 62 754 = 08193 64 752 = 08193 74 985 = 10623 75 948 = 10263 75 984 = 10623 78 945 = 10263 81 492 = 05763 81 645 = 07293 82 491 = 05763 84 975 = 10623 85 641 = 07293 85 974 = 10623 91 482 = 05763 91 752 = 08463 92 481 = 05763 92 751 = 08464 35 987 = 10264 37 985 = 10264 38 579 = 06214 39 578 = 06214 52 763 = 08194 53 762 = 08194 62 753 = 08194 62 987 = 10534 63 752 = 08194 67 982 = 10534 68 279 = 03514 69 278 = 03514 73 985 = 10624 75 983 = 10624 78 269 = 03514 78 539 = 06214 79 268 = 03514 79 538 = 06214 82 967 = 10534 83 975 = 10624 85 937 = 10264 85 973 = 10624 87 935 = 10264 87 962 = 10535 34 987 = 10265 37 984 = 10265 41 683 = 07295 41 692 = 07385 42 691 = 07385 43 681 = 07295 43 978 = 10265 48 973 = 10265 71 392 = 04685 72 391 = 04685 73 948 = 10265 73 984 = 10625 74 983 = 10625 78 943 = 10265 81 643 = 07295 83 641 = 07295 83 974 = 10625 84 937 = 10265 84 973 = 10625 87 934 = 10265 91 372 = 04685 91 642 = 07385 92 371 = 04685 92 641 = 07386 27 498 = 05316 28 479 = 05136 28 497 = 05316 29 478 = 05136 42 987 = 10356 47 298 = 03516 47 982 = 10356 48 297 = 03516 58 179 = 02436 59 178 = 02436 71 382 = 04596 72 381 = 04596 78 159 = 02436 78 429 = 05136 79 158 = 02436 79 428 = 05136 81 372 = 04596 82 371 = 04596 82 947 = 10356 87 942 = 10356 97 248 = 03516 97 428 = 05316 98 247 = 03516 98 427 = 05317 26 498 = 05317 28 496 = 05317 34 985 = 10267 35 984 = 10267 42 986 = 10357 46 298 = 03517 46 982 = 10357 48 296 = 03517 58 169 = 02347 59 168 = 02347 62 984 = 10537 64 982 = 10537 68 159 = 02347 69 158 = 02347 82 946 = 10357 82 964 = 10537 84 935 = 10267 84 962 = 10537 85 934 = 10267 86 942 = 10357 96 248 = 03517 96 428 = 05317 98 246 = 03517 98 426 = 05318 26 479 = 05138 26 497 = 05318 27 496 = 05318 29 476 = 05138 34 579 = 06218 39 574 = 06218 43 975 = 10268 45 973 = 10268 46 297 = 03518 47 296 = 03518 56 179 = 02438 57 169 = 02348 59 167 = 02348 59 176 = 02438 64 279 = 03518 67 159 = 02348 69 157 = 02348 69 274 = 03518 73 945 = 10268 74 269 = 03518 74 539 = 06218 75 943 = 10268 76 159 = 02438 76 429 = 05138 79 156 = 02438 79 264 = 03518 79 426 = 05138 79 534 = 06218 96 247 = 03518 96 427 = 05318 97 246 = 03518 97 426 = 05319 26 478 = 05139 28 476 = 05139 34 578 = 06219 38 574 = 06219 56 178 = 02439 57 168 = 02349 58 167 = 02349 58 176 = 02439 64 278 = 03519 67 158 = 02349 68 157 = 02349 68 274 = 03519 74 268 = 03519 74 538 = 06219 76 158 = 02439 76 428 = 05139 78 156 = 02439 78 264 = 03519 78 426 = 05139 78 534 = 0621。
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