What is the sum of the first 25 odd natural numbers?
1). 475
2). 575
3). 600
4). 625
The numbers are 1, 3, 5, 7…., 49
Sum of n terms of an AP = n/2 × {2a + (n - 1)d}
Where a is the first term, n is the number of terms and d is the common difference
First term of the series (a) is 1
Common difference (d) = 3 - 1 = 2 and n is 25
Sum = 25/2 × (2 + 24 × 2) = 625