CBSE Class 10 Mathematics Standard 2026: question 31
Set in the CBSE Class 10 board exam of 2026, paper 30/5/1, section C, question 31, for 3 marks. Try it first; the hints and our step-by-step solution are below.
Q31 · 3 marks · Short answerCompetency-basedReal Numbers
The dimensions of a window are 156 cm 216 cm. Arjun wants to put grill on the window creating complete squares of maximum size. Determine the side length of the square and hence find the number of squares formed.
Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 30/5/1.
Hints
Open one hint at a time and try again before the next.
Hint 1
The square's side must divide both 156 and 216 exactly.
Hint 2
Maximum size means the greatest common divisor — find the HCF by prime factorisation.
Hint 3
Divide the window area by the area of one square.
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.
- ½ mark
- ½ mark
- 1 mark
The largest square that fits exactly along both sides has side = HCF(156, 216) cm.
- 1 mark
Number of squares
Answer: Side of square = 12 cm; number of squares = 234
Where the marks are
- Prime factorisation of 156 (½ mark)
- Prime factorisation of 216 (½ mark)
- Side = HCF = 12 cm (1 mark)
- Number of squares = 234 (1 mark)
Revise the chapter
- Chapter: Real Numbers (notes, formulas, where marks are lost and every past question)
- Topic: HCF and LCM by Prime Factorisation
More questions from Real Numbers
- Sample paper 2025-26 (Standard), Q1 · 1 markIf a = 2² × 3^x, b = 2² × 3 × 5, c = 2² × 3 × 7 and LCM (a,b,c) = 3780, then x is equal to
- Sample paper 2025-26 (Standard), Q10 · 1 markThe sum of two numbers is 1215 and their HCF is 81, then the possible pairs of such numbers are
- 2025 board paper, set 30/2/1 (Standard), Q4 · 1 markThe least number which is a perfect square and is divisible by each of 16, 20 and 50, is :
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.