What is the sum of the first (150) natural numbers?
Answer and explanation
Correct answer: 11325
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{150}=\frac{150\times151}{2}=75\times151=11325\). Hence, 11325 is correct. A value such as 11225 may result from incorrectly using \(150\times150/2\); the formula must include \(n+1\). Exam tip: write \(\frac{n(n+1)}{2}\) first, then simplify the calculation.
Frequently asked questions
What is the correct answer to this question?
11325
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{150}=\frac{150\times151}{2}=75\times151=11325\). Hence, 11325 is correct. A value such as 11225 may result from incorrectly using \(150\times150/2\); the formula must include \(n+1\). Exam tip: write \(\frac{n(n+1)}{2}\) first, then simplify the calculation.
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.
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