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Class 9 Mathematics Sequences and Progressions Sum of first n natural numbersEasyLevel 63

If (1+2+3+\cdots+n=210), what is (n)?

Answer and explanation

Correct answer: (20)

(S_{20}=\frac{20\times21}{2}=210), so (n=20). For a larger sum, checking through options is simple.

Tags

mathsequencesnatural-numberssum

Frequently asked questions

What is the correct answer to this question?

(20)

Why is this the correct answer?

(S_{20}=\frac{20\times21}{2}=210), so (n=20). For a larger sum, checking through options is simple.

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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