How much is the sum of the first (42) natural numbers?
Answer and explanation
Correct answer: 903
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=42\), we get \(\frac{42\times43}{2}=21\times43=903\). The value \(882\) comes from using \(42\times21\) and misses the required \(n+1=43\) factor. Exam tip: always include \(n+1\) when applying this sum formula.
Frequently asked questions
What is the correct answer to this question?
903
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(\frac{n(n+1)}{2}\). Substituting \(n=42\), we get \(\frac{42\times43}{2}=21\times43=903\). The value \(882\) comes from using \(42\times21\) and misses the required \(n+1=43\) factor. Exam tip: always include \(n+1\) when applying this sum formula.
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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