当n=1时,{1},包含数字1的个数为1;
当n=5时,{1,2,3,4,5},包含数字1的个数为1;
当n=10时,{1,2,3,4,5,6,7,8,9,10},包含数字1的个数为2;
当n=15时,{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15},包含数字1的个数为8;
当n=999999999时,{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,...,999999999},包含数字1的个数为多少呢?
[ Last edited by HAT on 2008-11-12 at 23:52 ]
当n=5时,{1,2,3,4,5},包含数字1的个数为1;
当n=10时,{1,2,3,4,5,6,7,8,9,10},包含数字1的个数为2;
当n=15时,{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15},包含数字1的个数为8;
当n=999999999时,{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,...,999999999},包含数字1的个数为多少呢?
[ Last edited by HAT on 2008-11-12 at 23:52 ]

