The sum of the first (60) natural numbers is (1830). What is the sum of the first (59) natural numbers?
Answer and explanation
Correct answer: 1770
The sum of the first 60 natural numbers includes the last number, 60. Therefore, subtract 60 to get the sum of the first 59 numbers: \(S_{59}=S_{60}-60=1830-60=1770\). Hence, 1770 is correct. Getting 1780 would mean subtracting 50, which is not the last term here. Exam tip: when reducing a consecutive natural-number sum by one term, subtract the omitted last term.
Frequently asked questions
What is the correct answer to this question?
1770
Why is this the correct answer?
The sum of the first 60 natural numbers includes the last number, 60. Therefore, subtract 60 to get the sum of the first 59 numbers: \(S_{59}=S_{60}-60=1830-60=1770\). Hence, 1770 is correct. Getting 1780 would mean subtracting 50, which is not the last term here. Exam tip: when reducing a consecutive natural-number sum by one term, subtract the omitted last term.
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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