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Ascending numbers! (Posted on 2003-05-25) Difficulty: 3 of 5
Let's call n an ascending number, if it has the following 2 properties:

- The number n has at least 2 digits.
- All digits of n are in ascending order, in base 10.

How many ascending numbers are there?

See The Solution Submitted by Fernando    
Rating: 2.3333 (3 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(2): solution | Comment 3 of 4 |
(In reply to re: solution by Sanjay)

Of course if you prefer the inclusion of leading zeros, then the number could have been gotten directly with 2^10-1-10 = 1013, the subtraction being for the one zero-digit possibility and for the 10 single-digit possibilities.
  Posted by Charlie on 2003-05-25 10:27:16

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