Find the sum of the first (47) natural numbers.
Answer and explanation
Correct answer: 1128
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{47}=\frac{47\times48}{2}=47\times24=1128\). Hence, option B is correct. Dividing \(48\) by \(2\) first makes the calculation simpler than multiplying \(47\times48\) directly. Exam tip: use \(n(n+1)/2\) for the sum of the first \(n\) natural numbers.
Frequently asked questions
What is the correct answer to this question?
1128
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{47}=\frac{47\times48}{2}=47\times24=1128\). Hence, option B is correct. Dividing \(48\) by \(2\) first makes the calculation simpler than multiplying \(47\times48\) directly. Exam tip: use \(n(n+1)/2\) 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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