Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and the Yahoo Answers website is now in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
Trending News
Combinatorics question?
How many different three digit positive integers are there? (No leading zeroes are
allowed.) How many positive integers with at most three digits? What are the
answers when “three” is replaced by “n?”
1 Answer
- ?Lv 78 years agoFavorite Answer
It will look like _ _ _. The first digit has 9 choices (1-9). For each of those, the second digit has 10 choices (0-9) and the same for the third digit. So there are 9 * 10^2 three digit positive integers.
At most 3 means it could have 1, 2, or 3 digits. That's all the integers from 1-999. So it is 999 = 10^3 - 1.
With n, question 1 becomes 9 * 10^(n-1).
Question 2 is 10^n - 1.
