What is the sum of the first 95 odd natural numbers?

2024

What is the sum of the first 95 odd natural numbers?

  1. A.

    1925

  2. B.

    4225

  3. C.

    9025

  4. D.

    11025

Attempted by 2 students.

Show answer & explanation

Correct answer: C

The sum of the first n odd natural numbers — 1, 3, 5, ..., up to the nth term — is a standard identity: it always equals n2. This holds because consecutive odd numbers form an arithmetic progression with first term 1 and common difference 2, and summing that progression algebraically reduces to a perfect square of the term count.

Applying this here:

  1. The number of terms to sum is n = 95 (the first 95 odd natural numbers).

  2. By the formula, the required sum is 952.

  3. Computing the square: 95 × 95 = 95 × 90 + 95 × 5 = 8550 + 475 = 9025.

This can be verified independently using the arithmetic-series sum formula, Sum = (n/2) × (first term + last term). The 95th odd number (the last term) is 2 × 95 − 1 = 189, so Sum = (95/2) × (1 + 189) = (95/2) × 190 = 95 × 95 = 9025 — the same result.

Hence, the sum of the first 95 odd natural numbers is 9025.

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