# What is the sum of an odd numbers between 1 to 50? - Algebra

Sum

What is the sum of an odd numbers between 1 to 50?

#### Solution

The odd numbers between 1 to 50 are

3, 5, 7, ......, 49

The above sequence is an A.P.

∴ a = 3, d = 5 – 3 = 2

Let the number of terms in the A.P. be n.

Then, tn = 49

Since tn = a + (n – 1)d,

49 = 3 + (n – 1)(2)

∴ 49 = 3 + 2n – 2

∴ 49 = 1 + 2n

∴ 48 = 2n

∴ n =48/2 = 24

Now, Sn = "n"/2 ("t"_1 + "t"_"n")

∴ S24 = 24/2 (3 + 49)

= 12(52)

= 624

∴ The sum of odd numbers between 1 to 50 is 624.

Concept: Sum of First n Terms of an AP
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