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prime-composite-lcm-hcf-l1 MCQ - Practice Questions with Answers

Solve 30 prime-composite-lcm-hcf-l1 questions for RAS/RPSC preparation.

Practice questions

Q1Which pair of numbers is co-prime?

A 8 and 12
B 9 and 15
C 14 and 25
D 21 and 28
Explanation

Co-prime numbers have HCF 1. The pair 14 and 25 has no common factor except 1, while 8 and 12 share 4, 9 and 15 share 3, and 21 and 28 share 7.

Q2Which statement correctly identifies a prime number?

A A number greater than 1 with exactly two factors, 1 and itself
B A number greater than 1 with more than two factors
C Any odd number
D A number that has 1 as its only factor
Explanation

A prime number is greater than 1 and has exactly two factors: 1 and itself. More than two factors makes a number composite, and being odd alone is not enough because 9 and 15 are odd but composite.

Q3Which number is neither prime nor composite?

A 1
B 2
C 9
D 15
Explanation

A prime number must be greater than 1 and have exactly two factors; a composite number must be greater than 1 and have more than two factors. The number 1 has only one factor, while 2 is prime and 9 and 15 are composite.

Q4How many composite numbers are there in the list 1, 2, 4, 6, 9, 11?

A 2
B 3
C 4
D 5
Explanation

A composite number is greater than 1 and has more than two factors. In the list, 4, 6 and 9 fit this rule; 1 is neither type, and 2 and 11 are prime.

Q5Which statement is incorrect?

A 9 is prime because it is odd.
B 2 is the only even prime number.
C 12 is composite because it has more than two factors.
D 1 is neither prime nor composite.
Explanation

The trap is confusing odd numbers with prime numbers. The factors of 9 are 1, 3 and 9, so it is composite, while the other three statements match the basic definitions.

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More questions

6The multiples of 4 are 4, 8, 12, 16, 20, 24, ... . The multiples of 6 are 6, 12, 18, 24, ... . What is the LCM of 4 and 6?

A2
B6
C24
D12

7Match the term with the best meaning: 1. HCF 2. LCM 3. Factor 4. Multiple

A1 least common multiple, 2 greatest common factor, 3 repeated jump, 4 exact divider
B1 greatest common factor, 2 least common multiple, 3 exact divider, 4 repeated jump
C1 exact divider, 2 repeated jump, 3 greatest common factor, 4 least common multiple
D1 repeated jump, 2 exact divider, 3 least common multiple, 4 greatest common factor

8A child says, 'Every odd number is prime.' Which teacher response is best?

AAgree, because all even numbers are composite.
BTell the child to memorise all primes without discussion.
CAsk the child to arrange 9 as 3 rows of 3 counters.
DChange the topic because odd and prime are unrelated.

9Using prime factorisation, what is the HCF of 36 and 48?

A6
B12
C24
D144

10Which method is best matched with the learning aim?

APrime number: first common landing point
BHCF: list multiples and choose the first shared number
CLCM: list factors and choose the greatest shared number
DComposite number: build more than one equal-row rectangle

11Imran arranges 13 counters. He can make only one rectangle: 1 by 13. What should the teacher say?

A13 is prime because its only factors are 1 and 13.
B13 is composite because it is odd.
C13 is neither prime nor composite like 1.
D13 is LCM because it is the smallest rectangle.

12What is the LCM of 4 and 6?

A2
B12
C24
D10

13Which statement correctly uses the definition of a prime number?

A17 is prime because its only factors are 1 and 17.
B1 is prime because it has only one factor.
C9 is prime because it is odd.
D2 is not prime because it is even.

14Which number can be the HCF of 18 and 30?

A6
B9
C15
D60

15During a factor-card activity, Tara uses a wheelchair and cannot reach the floor number line easily. What is the most inclusive teacher action?

ALet Tara only watch while other children jump.
BRemove the activity and give everyone a worksheet.
CAsk Tara to do only prime definitions orally later.
DGive Tara reachable factor cards and let her call or place shared factors.

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