What is half of the sum of the first (144) natural numbers?
Answer and explanation
Correct answer: 5220
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Thus, \(S_{144}=\frac{144\times145}{2}=10440\). Half of this sum is \(\frac{10440}{2}=5220\), so option B is correct. \(10440\) is the complete sum, not its half. Exam tip: After finding a sum, carefully apply any extra operation such as “half” or “double.”
Frequently asked questions
What is the correct answer to this question?
5220
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Thus, \(S_{144}=\frac{144\times145}{2}=10440\). Half of this sum is \(\frac{10440}{2}=5220\), so option B is correct. \(10440\) is the complete sum, not its half. Exam tip: After finding a sum, carefully apply any extra operation such as “half” or “double.”
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Sum of first n natural numbers.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
