The first digit can be formed in 8 ways (excluding 0 and 1). The rest of the 6 digits each can be filled in 10 ways. The total number of digits, therefore is 8 x 10^6.
It is 120 if the digits cannot be repeated.
81
823543
jfnvjsdkncjfdknvlakdjvbsadoihfcb shfvbcnsHLfc bnshJCbvjhbeshuyvbe b hdfbgehfgbwahucgbvfer fguy gyfuby uyr
Using your rule - essentially, it's the simplified sum of 9999999-2000000 which is a total of 7999999 numbers !
1 set
It is 120 if the digits cannot be repeated.
81
823543
jfnvjsdkncjfdknvlakdjvbsadoihfcb shfvbcnsHLfc bnshJCbvjhbeshuyvbe b hdfbgehfgbwahucgbvfer fguy gyfuby uyr
Using your rule - essentially, it's the simplified sum of 9999999-2000000 which is a total of 7999999 numbers !
4*3*2*1 = 24
3x3x3=27
24
500
7
There are 5! = 120 such numbers.