Find the sum of the first (13) natural numbers.
Answer and explanation
Correct answer: 91
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=13\), we get \(\frac{13\times14}{2}=13\times7=91\). Therefore, 91 is correct. 84 is less than the actual sum of 13 natural numbers. Exam tip: For the sum from 1 to \(n\), directly use \(\frac{n(n+1)}{2}\).
Frequently asked questions
What is the correct answer to this question?
91
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=13\), we get \(\frac{13\times14}{2}=13\times7=91\). Therefore, 91 is correct. 84 is less than the actual sum of 13 natural numbers. Exam tip: For the sum from 1 to \(n\), directly use \(\frac{n(n+1)}{2}\).
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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