Find the sum of all odd numbers upto 100.

1.	Find the sum of all odd numbers upto 100.
Answer» The given numbers are 1, 3, 5, 7, ..., 99. This is an A.P. with a = 1 and d = 2. Let it contain n terms. Then, 1 + (n - 1) x 2 = 99 or n = 50. Required sum = n/2 (first term + last term) = 50/2 (1 + 99) = 2500.

Answer»

The given numbers are 1, 3, 5, 7, ..., 99.

This is an A.P. with a = 1 and d = 2.

Let it contain n terms. Then,

1 + (n - 1) x 2 = 99 or n = 50.

Required sum = n/2 (first term + last term)

= 50/2 (1 + 99)

= 2500.

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