Quantitative Aptitude — MCQ Practice Questions & Answers

Question 1

Find the HCF of 48 and 64.

Accepted Answer

Correct answer: B. 16 — Using prime factorization: 48 = 2⁴ × 3, 64 = 2⁶. HCF = 2⁴ = 16 (taking lowest powers of common prime factors).

Answer

A. 8

Answer

C. 32

Answer

D. 24

Question 2

What is the LCM of 12 and 18?

Accepted Answer

Correct answer: A. 36 — Prime factorization: 12 = 2² × 3, 18 = 2 × 3². LCM = 2² × 3² = 4 × 9 = 36 (taking highest powers of all prime factors).

Answer

B. 24

Answer

C. 54

Answer

D. 72

Question 3

Find the HCF of 56 and 72.

Accepted Answer

Correct answer: B. 8 — This question asks us to find the Highest Common Factor (HCF) of two numbers using prime factorization or the Euclidean algorithm. Step 1: Prime factorization of 56 Express 56 as a product of prime numbers. 56 = 2 	imes 2 	imes 2 	imes 7 = 2^3 	imes 7 Step 2: Prime factorization of 72 Express 72 as a product of prime numbers. 72 = 2 	imes 2 	imes 2 	imes 3 	imes 3 = 2^3 	imes 3^2 Step 3: Find the HCF The HCF is the product of common prime factors with their lowest powers. 	ext{HCF} = 2^3 = 8 The HCF of 56 and 72 is 8, making the correct answer (B).

Answer

A. 4

Answer

C. 12

Answer

D. 16

Question 4

The LCM of 15 and 25 is:

Accepted Answer

Correct answer: A. 75 — This question asks us to find the Least Common Multiple (LCM) of two numbers using prime factorization. Step 1: Find prime factorization of 15 Break 15 into its prime factors. 15 = 3 	imes 5 Step 2: Find prime factorization of 25 Break 25 into its prime factors. 25 = 5 	imes 5 = 5^2 Step 3: Calculate LCM using highest powers of all prime factors The LCM is found by taking the highest power of each prime that appears in either factorization: 3¹ and 5². 	ext{LCM} = 3^1 	imes 5^2 = 3 	imes 25 = 75 The LCM of 15 and 25 is 75.

Answer

B. 150

Answer

C. 225

Answer

D. 300

Question 5

The product of two numbers is 2160 and their HCF is 12. Find their LCM.

Accepted Answer

Correct answer: A. 180 — Using the formula: HCF × LCM = Product of two numbers. Therefore, 12 × LCM = 2160, so LCM = 2160 ÷ 12 = 180.

Answer

B. 240

Answer

C. 300

Answer

D. 360

Question 6

What is the HCF of 18 and 27?

Accepted Answer

Correct answer: B. 9 — Factors of 18: 1, 2, 3, 6, 9, 18. Factors of 27: 1, 3, 9, 27. Common factors: 1, 3, 9. Highest common factor = 9.

Answer

A. 6

Answer

C. 12

Answer

D. 18

Question 7

Find the LCM of 20 and 30.

Accepted Answer

Correct answer: B. 60 — 20 = 2² × 5, 30 = 2 × 3 × 5. LCM = 2² × 3 × 5 = 4 × 3 × 5 = 60.

Answer

A. 30

Answer

C. 90

Answer

D. 120

Question 8

The LCM of two co-prime numbers is 221. What is the product of the numbers?

Accepted Answer

Correct answer: B. 221 — For co-prime numbers, HCF = 1. Using HCF × LCM = Product: 1 × 221 = Product. Therefore, product = 221.

Answer

A. 110

Answer

C. 442

Answer

D. 221

Quantitative Aptitude - MCQ Practice Questions