If (S_n=666), what will be (S_{n+1})?
Answer and explanation
Correct answer: 703
The sum of the first n natural numbers is \(S_n=\frac{n(n+1)}{2}\). From \(\frac{n(n+1)}{2}=666\), we get \(n=36\), since \(S_{36}=666\). Therefore, \(S_{n+1}=S_{37}=666+37=703\). The value 693 would result from adding 27, but the next natural number here is 37. Exam tip: use \(S_{n+1}=S_n+(n+1)\) directly.
Frequently asked questions
What is the correct answer to this question?
703
Why is this the correct answer?
The sum of the first n natural numbers is \(S_n=\frac{n(n+1)}{2}\). From \(\frac{n(n+1)}{2}=666\), we get \(n=36\), since \(S_{36}=666\). Therefore, \(S_{n+1}=S_{37}=666+37=703\). The value 693 would result from adding 27, but the next natural number here is 37. Exam tip: use \(S_{n+1}=S_n+(n+1)\) 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.
