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Class 7 Finding Common Ground worksheet
CBSE Mathematics. Prime factorisation, HCF and LCM of two and three numbers, HCF × LCM, co-primes, tiles, bells and packing. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
The prime factorisation of 225 is:
- 3 × 3 × 5 × 5
- 3 × 3 × 5 × 5 × 2
- 9 × 5 × 5
- 3 × 3 × 5 × 10
Answer
(a) 3 × 3 × 5 × 5
3 × 3 × 5 × 5 = 225, all prime
- 2.
The HCF of 319 and 290 is:
- 29
- 3190
- 58
- 110
Answer
(a) 29
319 = 29 × 11, 290 = 29 × 10
- 3.
HCF stands for:
- Highest Counting Figure
- Half Common Factor
- Highest Common Factor
- Highest Common Fraction
Answer
(c) Highest Common Factor
Section B · short answer
- 4.
Write 1512 as a product of prime factors, using powers.
Answer
2³ × 3³ × 7
2 × 2 × 2 × 3 × 3 × 3 × 7 = 1512
- 5.
Find the HCF of 77 and 70 by prime factorisation.
Answer
7
7 × 11 and 2 × 5 × 7: common primes give 7 = 7
Section C · long answer
- 6.
Three traffic lights change every 48, 20 and 24 seconds. They change together at 9:00:00 am. When do they next change together?
Answer
after 240 seconds, at 9:04:00 am
LCM of 48, 20 and 24 = 240 s = 4 min 0 s
Fresh sheets for your child
In the app, every Finding Common Ground sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
Coming soon for Android and iPhone.