Choose the sum of the first (30) natural numbers.
Answer and explanation
Correct answer: 465
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=30\) gives \(\frac{30\times31}{2}=15\times31=465\). A value such as \(435\) can result from incorrectly using \(30\times29/2\). Exam tip: for the sum of natural numbers, always use \(n+1\) in the formula.
Frequently asked questions
What is the correct answer to this question?
465
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=30\) gives \(\frac{30\times31}{2}=15\times31=465\). A value such as \(435\) can result from incorrectly using \(30\times29/2\). Exam tip: for the sum of natural numbers, always use \(n+1\) in the formula.
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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