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Question
Find the sum of first 1000 positive integers.
Activity :- Let 1 + 2 + 3 + ........ + 1000
Using formula for the sum of first n terms of an A.P.,
Sn = `square`
S1000 = `square/2 (1 + 1000)`
= 500 × 1001
= `square`
Therefore, Sum of the first 1000 positive integer is `square`
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Solution
Let 1 + 2 + 3 + ........ + 1000
Using formula for the sum of first n terms of an A.P.,
Sn = `"n"/2 ("t"_1 + "t"_"n")`
S1000 = `1000/2 (1 + 1000)`
= 500 × 1001
= 500500
Therefore, Sum of the first 1000 positive integer is 500500.
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