7X6X5X4X3/(5X4X3X2)=21组
12345 12346 12347
12356 12357 12367
12456 12457 12467
12567 13456 13457
13467 13567 14567
23456 23457 23467
23567 24567 34567
共以上21种组合
7X6X5X4X3/(5X4X3X2)=21组
12345 12346 12347
12356 12357 12367
12456 12457 12467
12567 13456 13457
13467 13567 14567
23456 23457 23467
23567 24567 34567
共以上21种组合