10C2 = 45
9,999 different combos well 10,00 if you add 0 in with it
10,000
start with the 100's place 0 = 0+0 1 = 1+0 = 0+1 2 = 1+1=2+0=0+2 3 = 3+0 = 2+1 = 1+2 = 0+3 ... with the 100's digit, the number of such numbers is one greater than that number 0 : 1 1 : 2 ... therefore there are 1+2+3+4+5+6+7+8+9+10 = 5*11 = 55 such numbers unless you don't count 000 as a three digit number, then there are 54 such numbers.
10,000
hi wazup hi wazup
100,000
81
There are 900 of them.
10,000
100000 - including numbers with leading 0s
There are 76 such numbers. Eight more if you allow numbers to start with 0.
There are 7*94 = 45927 such numbers.
Using your rule - essentially, it's the simplified sum of 9999999-2000000 which is a total of 7999999 numbers !
There are 8*9*8*7*6*5*4 = 483840 numbers.
9,999 different combos well 10,00 if you add 0 in with it
8*10*10=800
Only four numbers:20233032