SOLUTION: How many natural number between 1000 and 1999 (both exclusive) have atleast one of their digit is repeated?

Question 793188: How many natural number between 1000 and 1999 (both exclusive) have atleast one of their digit is repeated?
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!
There are 1998-1000=998 numbers to consider.
The ones that do not have a 1 in the last 3 digits, and do not have another digit repeated are because we have 9 digits to chose from (0, 2, 3, ...8, 9) for the hundreds digit, 8 for the tens, and 7 for the ones.
Those 504 numbers are the ones without any digit repeated.
The remaining have at least one digit repeated.
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