How much less is the sum of the first (99) natural numbers than the sum of the first (100) natural numbers?
Answer and explanation
Correct answer: 100
The sum of the first 100 natural numbers contains exactly one additional term beyond the sum of the first 99 natural numbers: 100. Therefore, \(S_{100}-S_{99}=100\). Option 99 is the last number among the first 99 natural numbers, not the difference between the two sums. Exam tip: The difference between sums of consecutive natural-number terms is always the next natural number.
Frequently asked questions
What is the correct answer to this question?
100
Why is this the correct answer?
The sum of the first 100 natural numbers contains exactly one additional term beyond the sum of the first 99 natural numbers: 100. Therefore, \(S_{100}-S_{99}=100\). Option 99 is the last number among the first 99 natural numbers, not the difference between the two sums. Exam tip: The difference between sums of consecutive natural-number terms is always the next natural number.
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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