Find the sum of the first (9) natural numbers.
Answer and explanation
Correct answer: 45
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=9\), we get \(\frac{9\times10}{2}=45\). Therefore, 45 is correct. The value 36 is the sum of natural numbers from 1 to 8, so it is a close but incorrect option. Exam tip: remember \(\frac{n(n+1)}{2}\) for the sum of the first \(n\) natural numbers.
Frequently asked questions
What is the correct answer to this question?
45
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=9\), we get \(\frac{9\times10}{2}=45\). Therefore, 45 is correct. The value 36 is the sum of natural numbers from 1 to 8, so it is a close but incorrect option. Exam tip: remember \(\frac{n(n+1)}{2}\) for the sum of the first \(n\) natural numbers.
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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