What is 25% of the sum of the first 56 natural numbers?
Answer and explanation
Correct answer: 399
The sum of the first 56 natural numbers is S₅₆ = 56 × 57/2 = 28 × 57 = 1596. Since 25% equals 25/100 = 1/4, the required value is 25% of 1596 = 1596/4 = 399. Therefore option A is correct. A useful check is that 400 × 4 = 1600, so one quarter of 1596 must be 399. The other choices are close values but do not equal one-fourth of the calculated sum; they may result from an incorrect sum formula, a percentage-conversion error, or faulty division. Both stages—finding S₅₆ and converting 25% to one-fourth—are essential.
Frequently asked questions
What is the correct answer to this question?
399
Why is this the correct answer?
The sum of the first 56 natural numbers is S₅₆ = 56 × 57/2 = 28 × 57 = 1596. Since 25% equals 25/100 = 1/4, the required value is 25% of 1596 = 1596/4 = 399. Therefore option A is correct. A useful check is that 400 × 4 = 1600, so one quarter of 1596 must be 399. The other choices are close values but do not equal one-fourth of the calculated sum; they may result from an incorrect sum formula, a percentage-conversion error, or faulty division. Both stages—finding S₅₆ and converting 25% to one-fourth—are essential.
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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