What is half of the sum of the first (40) natural numbers?
Answer and explanation
Correct answer: 410
The sum of the first 40 natural numbers is \\(S=\frac{40\times41}{2}=820\\). Half of this sum is \\(\frac{820}{2}=410\\), so option B is correct. Getting 420 would result from an error while finding the sum or taking half of it. Exam tip: remember that the sum of the first n natural numbers is \\(\frac{n(n+1)}{2}\\).
Frequently asked questions
What is the correct answer to this question?
410
Why is this the correct answer?
The sum of the first 40 natural numbers is \\(S=\frac{40\times41}{2}=820\\). Half of this sum is \\(\frac{820}{2}=410\\), so option B is correct. Getting 420 would result from an error while finding the sum or taking half of it. Exam tip: remember that the sum of the first n natural numbers is \\(\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.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
