Grade 5 Math Olympiad Number System Questions (59 Practice Questions + Easy Explanations)

Introduction: Why These Topics Matter More Than You Think

If you ask most Grade 5 students what they think about math, you’ll usually hear one of two answers: “It’s fun!” or “It’s confusing!”

The truth is—math becomes fun only when the basics are clear.

Math Olympiad questions are not just about solving sums quickly. They test how well a student understands concepts like numbers, patterns, and operations. And at the Grade 5 level, topics such as large numbers, factors, multiples, and basic operations form the backbone of everything that comes later.

Think of it like building a house. If the foundation is weak, nothing stands strong. But if the basics are clear, even the toughest problems start to feel manageable.

In this article, we’ll go topic by topic, explain each concept in a simple way, and give you 59 practice questions to sharpen your skills.

 1. Large Numbers (7 & 8 Digits)

 Understanding the Concept

Large numbers may look scary at first, but they are just numbers with more digits. The key is to understand place value.

For example:
45,678,912 is not just a long number—it tells a story:

• 45 million

• 678 thousand

• 912

Once you learn to break numbers into parts, reading and writing them becomes much easier.

Practice Questions (1–8)

1. Write 7,456,321 in words

2. Write 23,456,789 in words

3. What is the place value of 6 in 56,78,912?

4. Write the number name: 90,45,123

5. Arrange in ascending order: 45,67,123; 45,67,213; 45,76,123

6. Form the largest number using digits: 4, 7, 2, 9, 1, 8, 3

7. What is 1 more than 99,99,999?

8. Write the smallest 8-digit number

2. Number Names

 Why This Is Important

Many students lose marks in Olympiads not because they don’t understand math—but because they misread numbers.

Being comfortable with number names helps avoid silly mistakes and improves clarity.

 Practice Questions (9–14)

9. Write 34,56,789 in words

10. Write in numerals: Fifty-six lakh twenty-three thousand one hundred

11. Write 70,08,009 in words

12. Expand: 45,67,123

13. Write in standard form: 30,00,000 + 5,00,000 + 60,000 + 2,000 + 300

14. Identify the error: Forty lakh fifty thousand ten

 3. Factors and Multiples

 Simple Way to Understand

Think of factors as numbers that divide exactly, and multiples as numbers you get when you multiply.

For example:

• Factors of 12 → numbers that divide 12

• Multiples of 12 → 12, 24, 36, 48…

This topic is very important because it leads directly to HCF and LCM.

 Practice Questions (15–22)

15. List all factors of 24

16. Find first 5 multiples of 9

17. Is 36 a multiple of 6?

18. Find common factors of 12 and 18

19. Find smallest multiple of 7 greater than 50

20. Is 1 a factor of every number?

21. Find number of factors of 16

22. True/False: Every multiple of 5 ends with 5

 4. HCF and LCM

 Making It Easy

Students often confuse HCF and LCM, but here’s a simple trick:

• HCF → Smaller (common divisor)

• LCM → Bigger (common multiple)

These concepts are often used in real-life situations like grouping or scheduling.

 Practice Questions (23–30)

23. Find HCF of 12 and 18

24. Find LCM of 4 and 6

25. Find HCF of 24 and 36

26. Find LCM of 8 and 12

27. Two numbers have HCF 5 and LCM 60. Find one possible pair

28. Find HCF of 15, 25, 35

29. Find LCM of 3, 4, 5

30. True/False: HCF is always smaller than LCM

 5. Prime Factorization

 Why It Matters

Prime factorization is like breaking a number into its smallest building blocks.

Once you understand this, HCF and LCM become much easier.

 Practice Questions (31–38)

31. Prime factorize 18

32. Prime factorize 36

33. Prime factorize 45

34. Is 29 a prime number?

35. Find prime factors of 50

36. Write smallest prime number

37. Write even prime number

38. Find product of prime factors of 20

 6. Multiplication

 Tips for Students

Multiplication in Olympiads is not just about getting answers—it’s about doing it smartly:

• Break numbers

• Use patterns

• Estimate before solving

 Practice Questions (39–45)

39. 456 × 23

40. 1,234 × 5

41. 789 × 12

42. Multiply: 4,567 × 10

43. Find product: 2,345 × 20

44. Estimate: 498 × 9

45. Find missing number: __ × 5 = 2,500

 7. Division

 Keep This in Mind

Division becomes easy when multiplication is strong. Always check your answers by multiplying back.

 Practice Questions (46–52)

46. 1,200 ÷ 6

47. 4,500 ÷ 9

48. 3,456 ÷ 8

49. 9,999 ÷ 3

50. Divide: 7,200 ÷ 10

51. Find remainder: 55 ÷ 6

52. Find quotient: 8,400 ÷ 7

 8. Roman Numerals

Fun but Tricky

Roman numerals are fun once you learn the rules. Just remember:

• Smaller before bigger = subtract

• Smaller after bigger = add

 Practice Questions (53–59)

53. Write 25 in Roman numerals

54. Write 49 in Roman numerals

55. Convert XL to number

56. Convert XC to number

57. Write 100 in Roman numerals

58. What is L + X?

59. Write 39 in Roman numerals

Math Olympiad success doesn’t happen overnight. It builds slowly—through practice, mistakes, and learning.

If you’re a student reading this:
Start small. Don’t worry about getting everything right.

If you’re a parent:
Focus on encouraging effort, not just results.

These Grade 5 topics may seem basic, but they are incredibly powerful. Once they are clear, higher-level math becomes much easier—and much more enjoyable.

So take your time, practice regularly, and most importantly—don’t be afraid of challenging questions. That’s where real learning happens.