Questions with Answers on Prime and Composite Numbers for Grade 5

Grade 5 maths questions on prime and composite numbers are presented along with detailed step-by-step solutions and explanations.

Questions and Step-by-Step Solutions

  1. Question 1: True or False: All prime numbers are odd.

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    False: The number 2 is even, yet it is prime because its only divisors are 1 and 2.

  2. Question 2: What is the smallest prime number?

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    A prime number is a whole number greater than 1 whose only divisors are 1 and itself.
    - 1 is neither prime nor composite.
    - 2 has only two divisors (1 and 2), making it the smallest prime number.
    Answer: 2

  3. Question 3: True or False: All even numbers greater than 2 are composite.

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    True: Every even number greater than 2 can be divided evenly by 2 (in addition to 1 and itself), which means it has more than two divisors and is therefore composite.

  4. Question 4: Which of the following numbers is prime?
    A) 12      B) 6      C) 9      D) 7

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    - 12 is composite (divisible by 1, 2, 3, 4, 6, 12).
    - 6 is composite (divisible by 1, 2, 3, 6).
    - 9 is composite (divisible by 1, 3, 9).
    - 7 is prime (divisible only by 1 and 7).
    Therefore, option D is correct.

  5. Question 5: Which of the following numbers is composite?
    A) 21      B) 2      C) 13      D) 11

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    - 21 is composite (divisible by 1, 3, 7, 21).
    - 2 is prime.
    - 13 is prime.
    - 11 is prime.
    Therefore, option A is correct.

  6. Question 6: Which of the following numbers is prime?
    A) 27      B) 31      C) 1      D) 39

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    - 27 is composite (divisible by 1, 3, 9, 27).
    - 31 is prime (divisible only by 1 and 31).
    - 1 is neither prime nor composite.
    - 39 is composite (divisible by 1, 3, 13, 39).
    Therefore, option B is correct.

  7. Question 7: Which of the following numbers is composite?
    A) 1      B) 57      C) 17      D) 41

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    - 1 is neither.
    - 57 is composite (divisible by 1, 3, 19, 57).
    - 17 is prime.
    - 41 is prime.
    Therefore, option B is correct.

  8. Question 8: Which number is neither prime nor composite?
    A) 15      B) 41      C) 18      D) 1

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    The number 1 has only one divisor (1 itself), so by definition it is neither prime nor composite.
    Therefore, option D is correct.

  9. Question 9: Classify each of the following numbers as prime or composite: 16, 24, 29, 30, 31, 33, 81, 97, 100, 101

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    - 16: Composite (divisible by 2, 4, etc.)
    - 24: Composite (divisible by 2, 3, etc.)
    - 29: Prime
    - 30: Composite (divisible by 2, 3, 5, etc.)
    - 31: Prime
    - 33: Composite (divisible by 3, 11)
    - 81: Composite (divisible by 3, 9, etc.)
    - 97: Prime
    - 100: Composite (divisible by 2, 5, etc.)
    - 101: Prime

    Summary:
    Prime: 29, 31, 97, 101
    Composite: 16, 24, 30, 33, 81, 100

  10. Question 10: List all prime numbers from 2 to 31.

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    Checking numbers from 2 to 31 for divisors other than 1 and themselves:
    2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31

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