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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 = \[\boxed{\frac{n}{2} (t_1 + t_n)}\]
S1000 = \[\frac{\boxed{1000}}{2} (1 + 1000)\]
= 500 × 1001
= \[\boxed{500500}\]
Therefore, Sum of the first 1000 positive integer is \[\boxed{500500}\].
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