What is the sum of the first (100) natural numbers?
Answer and explanation
Correct answer: 5050
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=100\), we get \(\frac{100\times101}{2}=5050\). The value \(5000\) results from incorrectly using \(100\times100/2\) and missing the \(n+1=101\) factor. Exam tip: For \(1+2+\cdots+n\), apply \(\frac{n(n+1)}{2}\) directly.
Frequently asked questions
What is the correct answer to this question?
5050
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=100\), we get \(\frac{100\times101}{2}=5050\). The value \(5000\) results from incorrectly using \(100\times100/2\) and missing the \(n+1=101\) factor. Exam tip: For \(1+2+\cdots+n\), apply \(\frac{n(n+1)}{2}\) directly.
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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