What will be the sum of the first (8) natural numbers?
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Answer and explanation
Correct answer: 36
The first 8 natural numbers are 1 to 8. Their sum is found using \(S_n=\frac{n(n+1)}{2}\). Thus, \(S_8=\frac{8(8+1)}{2}=\frac{8\times9}{2}=36\). The value 40 would result from adding 1 to 9 rather than 1 to 8. Exam tip: use \(\frac{n(n+1)}{2}\) for the sum of the first \(n\) natural numbers.
Frequently asked questions
What is the correct answer to this question?
36
Why is this the correct answer?
The first 8 natural numbers are 1 to 8. Their sum is found using \(S_n=\frac{n(n+1)}{2}\). Thus, \(S_8=\frac{8(8+1)}{2}=\frac{8\times9}{2}=36\). The value 40 would result from adding 1 to 9 rather than 1 to 8. Exam tip: use \(\frac{n(n+1)}{2}\) 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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