How much is the sum of natural numbers from (101) to (160)?
Answer and explanation
Correct answer: 7830
To find the sum from 101 to 160, subtract the sum from 1 to 100 from the sum from 1 to 160. Thus, \(S_{160}-S_{100}=\frac{160\times161}{2}-\frac{100\times101}{2}=12880-5050=7830\). Hence, 7830 is the correct answer. An option such as 7780 can result from a small subtraction or multiplication error. Exam tip: for a range of consecutive natural numbers, use \(S_n=\frac{n(n+1)}{2}\).
Frequently asked questions
What is the correct answer to this question?
7830
Why is this the correct answer?
To find the sum from 101 to 160, subtract the sum from 1 to 100 from the sum from 1 to 160. Thus, \(S_{160}-S_{100}=\frac{160\times161}{2}-\frac{100\times101}{2}=12880-5050=7830\). Hence, 7830 is the correct answer. An option such as 7780 can result from a small subtraction or multiplication error. Exam tip: for a range of consecutive natural numbers, use \(S_n=\frac{n(n+1)}{2}\).
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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