Find the sum of natural numbers from (151) to (225).
Answer and explanation
Correct answer: 14100
There are \(225-151+1=75\) terms from 151 to 225. Their average is \(\frac{151+225}{2}=188\). Therefore, the sum is \(75\times188=14100\). A value such as 14050 can result from counting the terms or the last term incorrectly. Exam tip: for consecutive numbers, use \(\text{number of terms}\times\text{average}\) for a quick calculation.
Frequently asked questions
What is the correct answer to this question?
14100
Why is this the correct answer?
There are \(225-151+1=75\) terms from 151 to 225. Their average is \(\frac{151+225}{2}=188\). Therefore, the sum is \(75\times188=14100\). A value such as 14050 can result from counting the terms or the last term incorrectly. Exam tip: for consecutive numbers, use \(\text{number of terms}\times\text{average}\) for a quick calculation.
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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