SOLUTION: Find the sum of positive integers between 100 and 999 inclusive which are odd.

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Question 1190792: Find the sum of positive integers between 100 and 999 inclusive which are odd.
Answer by ikleyn(52787) About Me  (Show Source):
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Find the sum of positive integers between 100 and 999 inclusive which are odd.
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First term is 101.  The last term is 999.


Their average is  %28101%2B999%29%2F2 = 1100%2F2 = 550.


The number of terms is  %28999-101%29%2F2%2B1 = 898%2F2%2B1 = 450.


The sum is  S = %28%28a%5B1%5D%2Ba%5Bn%5D%29%2F2%29%2An = 550*450 = 247500.    ANSWER

Solved.

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For introductory lessons on arithmetic progressions see
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
    - Word problems on arithmetic progressions
in this site.

Also,  you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Arithmetic progressions".


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Free of charge online textbook in ALGEBRA-II
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