What is the sum of the first (15) odd natural numbers?
Answer and explanation
Correct answer: 225
The first 15 odd natural numbers are 1, 3, 5, ..., 29. The sum of the first n odd natural numbers is n². Therefore, the sum is 15² = 225. A value such as 215 does not give the correct sum for this sequence with common difference 2. Exam tip: Remember that the sum of the first n odd numbers is n².
Frequently asked questions
What is the correct answer to this question?
225
Why is this the correct answer?
The first 15 odd natural numbers are 1, 3, 5, ..., 29. The sum of the first n odd natural numbers is n². Therefore, the sum is 15² = 225. A value such as 215 does not give the correct sum for this sequence with common difference 2. Exam tip: Remember that the sum of the first n odd numbers is n².
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the sum of the first $n$ terms of an AP.
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