Find the sum of the first (55) natural numbers.
Answer and explanation
Correct answer: 1540
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{55}=\frac{55\times56}{2}=55\times28=1540\). Hence, 1540 is the correct option. The value \(1485\) is the sum up to 54, since \(\frac{54\times55}{2}=1485\). Exam tip: divide the even factor by 2 first to calculate quickly.
Frequently asked questions
What is the correct answer to this question?
1540
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{55}=\frac{55\times56}{2}=55\times28=1540\). Hence, 1540 is the correct option. The value \(1485\) is the sum up to 54, since \(\frac{54\times55}{2}=1485\). Exam tip: divide the even factor by 2 first to calculate quickly.
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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