What is the sum of the first (11) natural numbers?
Answer and explanation
Correct answer: 66
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). For \(n=11\), \(\frac{11\times12}{2}=11\times6=66\). Therefore, the correct answer is 66. Note that 55 is the sum of the first 10 natural numbers. Exam tip: substitute the value of \(n\) carefully in \(n(n+1)/2\).
Frequently asked questions
What is the correct answer to this question?
66
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). For \(n=11\), \(\frac{11\times12}{2}=11\times6=66\). Therefore, the correct answer is 66. Note that 55 is the sum of the first 10 natural numbers. Exam tip: substitute the value of \(n\) carefully in \(n(n+1)/2\).
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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