Time: 2 Hours | Maximum Marks: 80
๐น Section A โ MCQs (1 mark each)
- Which of the following is a prime number?
a) 27 b) 31 c) 39 d) 51 - The smallest composite number is:
a) 1 b) 2 c) 3 d) 4 - HCF of 12 and 18 is:
a) 2 b) 3 c) 6 d) 12 - LCM of 6 and 8 is:
a) 12 b) 24 c) 48 d) 6 - Which pair is co-prime?
a) (8, 16) b) (9, 27) c) (14, 15) d) (12, 18) - Number of factors of 16:
a) 3 b) 4 c) 5 d) 6 - Prime factorization of 20 is:
a) 2ร2ร5 b) 2ร10 c) 4ร5 d) 1ร20 - Which is NOT a prime number?
a) 11 b) 13 c) 15 d) 17 - LCM of 5 and 9:
a) 45 b) 14 c) 9 d) 5 - HCF of co-prime numbers is:
a) 0 b) 1 c) same number d) product
๐น Section B โ Fill in the Blanks (1 mark each)
- The factors of 1 are ______
- The smallest prime number is ______
- Even numbers are divisible by ______
- A number divisible by 10 must end in ______
- HCF of two identical numbers is ______
๐น Section C โ Short Answer (2 marks each)
- Find all factors of 30.
- Find the prime factorization of 84.
- Find the HCF of 20 and 25.
- Find the LCM of 10 and 12.
- Check if 97 is prime.
- Write first five multiples of 9.
- Write two composite numbers between 10 and 20.
- Check if 121 is a perfect square.
- Write two co-prime numbers.
- Find common factors of 16 and 24.
๐น Section D โ Case-Based Questions (3 marks each)
๐ Case 1: Classroom Arrangement
- A teacher has 40 pencils and 60 pens. She wants to distribute them equally among students.
a) Maximum number of students?
b) Items each student gets?
๐ Case 2: Traffic Signals
- Two traffic lights blink every 12 seconds and 18 seconds.
a) After how many seconds will they blink together?
b) Which concept is used?
๐ Case 3: Sweet Boxes
- A shopkeeper has 54 chocolates and 72 candies.
a) Maximum number of boxes?
b) Items per box?
๐ Case 4: Sports Teams
- 36 boys and 48 girls form equal teams.
a) Number of teams?
b) Members per team?
๐ Case 5: School Bell
- Bells ring every 5 and 7 minutes.
When will they ring together again?
๐น Section E โ Long Answer (4 marks each)
- Find HCF and LCM of 18 and 30. Verify relation.
- Find smallest number divisible by 3, 4, and 6.
- Find prime factorization of 96 using division method.
- Find HCF of 24, 36, and 60.
- Find LCM of 8, 12, and 15.
๐น Section F โ Higher Order Thinking (HOTS) (5 marks each)
- Find smallest number leaving remainder 1 when divided by 2, 3, 4.
- Find smallest number divisible by 4, 5, and 6.
- Two numbers have HCF = 6 and LCM = 180.
Find their product. - Find a number divisible by both 8 and 12 and lies between 50 and 100.
- A number is divisible by 3 and 5 but not by 2. Give one example.
๐น Section G โ Assertion & Reason (2 marks each)
- Assertion: 1 is a prime number
Reason: It has only one factor - Assertion: 2 is the only even prime number
Reason: All other even numbers are divisible by 2 - Assertion: HCF of co-primes is 1
Reason: They have no common factor except 1 - Assertion: LCM is always greater than HCF
Reason: LCM includes all prime factors - Assertion: 49 is prime
Reason: It has only two factors
๐น Section H โ Case Study (Real-Life Application) (5 marks each)
๐ Case Study 6: School Picnic
- 84 students and 126 sandwiches are to be divided equally.
a) Number of groups
b) Students per group
c) Sandwiches per group
๐ Case Study 7: Factory Packaging
- Boxes of 6 and 9 items are packed.
a) Smallest equal number
b) If tripled, new number
๐ Case Study 8: Festival Lights
- Lights blink every 8 and 10 seconds.
Find when they blink together 3rd time.
๐ Case Study 9: Book Stacking
- 45 books and 75 notebooks arranged equally
Find max groups and items
๐ Case Study 10: Sports Practice
- Players practice every 3, 4, and 6 days
Find next common practice day
โ FINAL ANSWER KEY (SHORT)
MCQs:
1-b, 2-d, 3-c, 4-b, 5-c, 6-c, 7-a, 8-c, 9-a, 10-b
Fill in blanks:
11. 1
12. 2
13. 2
14. 0
15. same number
Key Answers:
16. 1,2,3,5,6,10,15,30
17. 2ร2ร3ร7
18. 5
19. 60
20. Prime
21. 9,18,27,36,45
22. 12,14
23. Yes
24. (8,15)
25. 1,2,4,8
Case-Based Highlights:
26. 20 students, (2 pencils + 3 pens)
27. 36 sec, LCM
28. 18 boxes, (3 + 4)
29. 12 teams
30. 35 minutes
Long Answers:
31. HCF=6, LCM=90
32. 12
33. 2ร2ร2ร2ร2ร3
34. 12
35. 120
HOTS:
36. 13
37. 60
38. Product = 1080
39. 72 or 96
40. 15
Assertion:
41. False
42. True
43. True
44. True
45. False
Case Study:
46. 42 groups
47. 18 โ 54
48. 40 ร 3 = 120 sec
49. 15 groups
50. 12 days
