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3^n, where n is a natural… (Class 10 Maths Basic 2025, Q2)

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MathsCBSE Class 10 · Basic · Board exam 2025, set 430/3/1 · 1 mark · MCQ

CBSE Class 10 Mathematics Basic 2025: question 2

Set in the CBSE Class 10 board exam of 2025, paper 430/3/1, section A, question 2, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q2 · 1 mark · MCQReal Numbers

, where n is a natural number, cannot end with the digit:

  1. (A)3
  2. (B)5
  3. (C)7
  4. (D)9

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 430/3/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Work out and look at their last digits.

Hint 2

A number ending in 5 must be divisible by 5.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. The last digits of repeat in the cycle 3, 9, 7, 1.

  2. To end in 5 a number needs 5 as a prime factor, but has only the prime factor 3. So cannot end in 5.

    1 mark

Answer: 5, option (B)

Where the marks are

  • Identifies that 5 is not a factor of , so the last digit cannot be 5 (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Real Numbers, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 430/3/1 (Basic): every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.