Oh, dude, there are 90 two-digit numbers you can make from 0 to 9. You've got 10 options for the first digit (0-9) and 9 options for the second digit (0-9 excluding the one you already picked for the first digit). So, like, 10 times 9 equals 90. Math can be fun when you're making numbers do the cha-cha.
Well honey, there are 90 two-digit numbers that can be formed from 0 to 9. You see, you've got 10 choices for the tens digit (0-9) and 10 choices for the ones digit (0-9), giving you a total of 10 x 10 = 100 possible numbers. But we gotta subtract 10 numbers where both digits are the same (like 11, 22, 33, you get the idea), so that leaves us with 90 unique two-digit numbers. Hope that clears things up for ya!
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
Oh, what a happy little question! With the digits 1-9 and 0, you have 10 options for each digit in a 4-digit number. So, you can form 10 x 10 x 10 x 10 = 10,000 different 4-digit numbers. Isn't that just delightful? Just imagine all the beautiful combinations you can create!
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 !
9,999 different combos well 10,00 if you add 0 in with it
8*10*10=800
Only four numbers:20233032
18 (and 6 more starting with a 0).