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Discussion :: Numbers

  1. The sum of first 45 natural numbers is:

  2. A.

    1035

    B.

    1280

    C.

    2070

    D.

    2140

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    Answer : Option A

    Explanation :

    Let Sn = (1 + 2 + 3 + ... + 45)

    This is an A.P. in which a = 1, d = 1, n = 45 and l = 45

    Sn =\(\frac { n } { 2 } (a+1)\)=\( \frac { 45 } { 2 }\)x (1 + 45)   = (45 x 23)   = 1035

    Required sum = 1035.


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