State Exam — Quantitative Aptitude — HCF and LCM
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Showing 1–10 of 71 questions in HCF and LCM
Q.1 Medium HCF and LCM
Find the HCF and LCM of 36 and 48. What is their product?
A1728
B1440
C1296
D1680
Correct Answer:  A. 1728
Explanation:

36 = 2² × 3², 48 = 2⁴ × 3. HCF = 2² × 3 = 12, LCM = 2⁴ × 3² = 144.

Product = 36 × 48 = HCF × LCM = 12 × 144 = 1728.

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Q.2 Medium HCF and LCM
Two numbers have HCF of 8 and LCM of 96. If one number is 24, find the other number.
A32
B40
C48
D64
Correct Answer:  A. 32
Explanation:

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

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Q.3 Medium HCF and LCM
What is the HCF of 100, 150, and 200?
A25
B50
C75
D100
Correct Answer:  B. 50
Explanation:

100 = 2² × 5², 150 = 2 × 3 × 5², 200 = 2³ × 5².

Common factors: 2¹ × 5² = 2 × 25 = 50.

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Q.4 Medium HCF and LCM
Find the LCM of 84 and 140.
A420
B840
C210
D280
Correct Answer:  A. 420
Explanation:

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.

\[84 = 2^2 \times 3 \times 7\]
Step 2: Find prime factorization of 140

Break 140 into its prime factors by dividing by smallest primes.

\[140 = 2^2 \times 5 \times 7\]
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.

\[\text{LCM} = 2^2 \times 3 \times 5 \times 7 = 4 \times 3 \times 5 \times 7 = 420\]

The LCM of 84 and 140 is 420, which is option (A).

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Q.5 Medium HCF and LCM
The HCF of two numbers is 15. If their LCM is 180, and one number is 45, find the other number.
A45
B60
C75
D90
Correct Answer:  B. 60
Explanation:

Using HCF × LCM = Product of two numbers: 15 × 180 = 45 × other number.

Therefore, other number = 2700 ÷ 45 = 60.

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Q.6 Medium HCF and LCM
What is the HCF of 144 and 196?
A4
B8
C12
D16
Correct Answer:  A. 4
Explanation:

144 = 2⁴ × 3². 196 = 2² × 7².

Common prime factors: 2².

Therefore, HCF = 4.

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Q.7 Medium HCF and LCM
Two numbers are in the ratio 4:5, and their HCF is 6. Find the larger number.
A24
B30
C36
D48
Correct Answer:  B. 30
Explanation:

Let numbers be 4k and 5k. HCF = k = 6.

Therefore, numbers are 24 and 30.

The larger number is 30.

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Q.8 Medium HCF and LCM
The HCF of 56, 84, and 140 is:
A14
B28
C7
D4
Correct Answer:  A. 14
Explanation:

56 = 2³ × 7, 84 = 2² × 3 × 7, 140 = 2² × 5 × 7.

Common prime factors: 2 × 7 = 14.

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Q.9 Medium HCF and LCM
What is the LCM of 16, 24, and 36?
A72
B108
C144
D216
Correct Answer:  C. 144
Explanation:

16 = 2⁴, 24 = 2³ × 3, 36 = 2² × 3². LCM = 2⁴ × 3² = 16 × 9 = 144.

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Q.10 Medium HCF and LCM
If the HCF of two numbers is 18 and their LCM is 324, one number is 36. The other number is:
A162
B180
C196
D216
Correct Answer:  A. 162
Explanation:

HCF × LCM = Product of numbers. 18 × 324 = 36 × other.

Therefore, other = 5832 ÷ 36 = 162.

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