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
There are 8*9*8*7*6*5*4 = 483840 numbers.
jfnvjsdkncjfdknvlakdjvbsadoihfcb shfvbcnsHLfc bnshJCbvjhbeshuyvbe b hdfbgehfgbwahucgbvfer fguy gyfuby uyr
1 set
It is 120 if the digits cannot be repeated.
81
823543
There are 8*9*8*7*6*5*4 = 483840 numbers.
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 !
There are 5*4*3 = 60 such numbers.
4*3*2*1 = 24
27 if the digits can be repeated. 6 if not.
24
3x3x3=27