Find the sum: 1 + 3 + 5 + 7 + … + 99 (first 50 odd numbers):
A100
B250
C500
D2500
Answer & Solution
Correct answer: D. 2500
The sum of the first n odd natural numbers is n². For n = 50: 50² = 2500. (Quick alternative: S = n/2 × (first + last) = 50/2 × (1 + 99) = 25 × 100 = 2500.)
Related questions
The first two terms of the Fibonacci sequence are both:An A.P. written in standard form starts with a and then:In G.P. notation, l stands for the:The sum of cubes of the first n natural numbers is one of the:Which special series is studied as a sum to n terms?Besides progressions, the topic covers the relationship between A.M. and:The G.M. of two positive numbers is their geometric:The A.M. of two numbers is their arithmetic: