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

Find the HCF and LCM of 36 and 48. What is their product?

Accepted Answer

Correct answer: A. 1728 — 36 = 2² × 3², 48 = 2⁴ × 3. HCF = 2² × 3 = 12, LCM = 2⁴ × 3² = 144. Product = 36 × 48 = HCF × LCM = 12 × 144 = 1728.

Answer

B. 1440

Answer

C. 1296

Answer

D. 1680

Question 6

Two numbers have HCF of 8 and LCM of 96. If one number is 24, find the other number.

Accepted Answer

Correct answer: A. 32 — Using formula: HCF × LCM = Product of two numbers. 8 × 96 = 24 × x. 768 = 24x. x = 32.

Answer

B. 40

Answer

C. 48

Answer

D. 64

Question 7

What is the HCF of 100, 150, and 200?

Accepted Answer

Correct answer: B. 50 — 100 = 2² × 5², 150 = 2 × 3 × 5², 200 = 2³ × 5². Common factors: 2¹ × 5² = 2 × 25 = 50.

Answer

A. 25

Answer

C. 75

Answer

D. 100

Question 8

Find the LCM of 84 and 140.

Accepted Answer

Correct answer: A. 420 — This question asks us to find the least common multiple (LCM) of two numbers using prime factorization. Step 1: Find prime factorization of 84 Break 84 into its prime factors by dividing by smallest primes. 84 = 2^2 	imes 3 	imes 7 Step 2: Find prime factorization of 140 Break 140 into its prime factors by dividing by smallest primes. 140 = 2^2 	imes 5 	imes 7 Step 3: Calculate LCM using highest powers of all prime factors LCM is found by taking the highest power of each prime factor that appears in either number. 	ext{LCM} = 2^2 	imes 3 	imes 5 	imes 7 = 4 	imes 3 	imes 5 	imes 7 = 420 The LCM of 84 and 140 is 420, which is option (A).

Answer

B. 840

Answer

C. 210

Answer

D. 280

Quantitative Aptitude - MCQ Practice Questions