What is the value of (1+2+3+\cdots+27)?
Answer and explanation
Correct answer: 378
The sum of the first 27 natural numbers is found using \(S_n=\frac{n(n+1)}{2}\). Thus, \(S_{27}=\frac{27\times28}{2}=27\times14=378\). Therefore, 378 is correct. A value such as 364 can result from an arithmetic error while multiplying or dividing. Exam tip: Cancel the even factor with 2 before multiplying.
Frequently asked questions
What is the correct answer to this question?
378
Why is this the correct answer?
The sum of the first 27 natural numbers is found using \(S_n=\frac{n(n+1)}{2}\). Thus, \(S_{27}=\frac{27\times28}{2}=27\times14=378\). Therefore, 378 is correct. A value such as 364 can result from an arithmetic error while multiplying or dividing. Exam tip: Cancel the even factor with 2 before multiplying.
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.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
