What is the sum of (1+2+3+\cdots+50)?
Answer and explanation
Correct answer: 1275
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Here, \(n=50\), so \(\frac{50\times51}{2}=25\times51=1275\). Therefore, the correct answer is 1275. The value 1250 results from using \(50\times25\) without including \(n+1=51\). Exam tip: For the sum from 1 to \(n\), use \(\frac{n(n+1)}{2}\).
Frequently asked questions
What is the correct answer to this question?
1275
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Here, \(n=50\), so \(\frac{50\times51}{2}=25\times51=1275\). Therefore, the correct answer is 1275. The value 1250 results from using \(50\times25\) without including \(n+1=51\). Exam tip: For the sum from 1 to \(n\), use \(\frac{n(n+1)}{2}\).
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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