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Question (11)

QN0030483

Find the LCM of 16 and 20.

(A) 40
(B) 60
(C) 80
(D) 160

Correct Answer: C

Explanation:

16 = 2⁴ and 20 = 2² × 5. LCM = 2⁴ × 5 = 80.

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Question (12)

QN0030484

The LCM of 18 and 24 is:

(A) 36
(B) 48
(C) 72
(D) 96

Correct Answer: C

Explanation:

LCM = 2³ × 3² = 72.

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Question (13)

QN0030485

Which of the following is the smallest common multiple of 4 and 10?

(A) 10
(B) 20
(C) 30
(D) 40

Correct Answer: B

Explanation:

Multiples of 4 and 10 first meet at 20.

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Question (14)

QN0030486

Two children start clapping after every 6 seconds and 9 seconds respectively. They clap together now. After how many seconds will they clap together again?

(A) 12
(B) 18
(C) 24
(D) 36

Correct Answer: B

Explanation:

LCM of 6 and 9 is 18 seconds.

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Question (15)

QN0030487

Find the LCM of 21 and 28.

(A) 42
(B) 56
(C) 84
(D) 112

Correct Answer: C

Explanation:

21 = 3 × 7 and 28 = 2² × 7. LCM = 2² × 3 × 7 = 84.

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Question (16)

QN0030488

Which of the following is NOT a common multiple of 6 and 9?

(A) 18
(B) 36
(C) 45
(D) 54

Correct Answer: C

Explanation:

45 is divisible by 9 but not by 6.

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Question (17)

QN0030489

The prime factorisations of two numbers are: 24 = 2³ × 3 30 = 2 × 3 × 5 The LCM is:

(A) 60
(B) 90
(C) 120
(D) 240

Correct Answer: C

Explanation:

LCM = 2³ × 3 × 5 = 120.

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Question (18)

QN0030490

Find the LCM of 15, 20 and 30.

(A) 30
(B) 45
(C) 60
(D) 120

Correct Answer: C

Explanation:

LCM = 2² × 3 × 5 = 60.

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Question (19)

QN0030491

A machine starts automatically every 14 minutes, while another starts every 21 minutes. If both start together now, after how many minutes will they start together again?

(A) 28
(B) 35
(C) 42
(D) 84

Correct Answer: C

Explanation:

LCM of 14 and 21 is 42 minutes.

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Question (20)

QN0030492

Which statement about the Lowest Common Multiple (LCM) is true?

(A) Every common multiple is smaller than the LCM.
(B) The LCM is one of the common multiples and is the smallest among them.
(C) The LCM is always equal to the product of the numbers.
(D) Every multiple of one number is also a multiple of the other.

Correct Answer: B

Explanation:

The LCM is the least among all the common multiples.

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Question (11)

Find the LCM of 16 and 20.

Explanation:

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Question (12)

The LCM of 18 and 24 is:

Explanation:

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Question (13)

Which of the following is the smallest common multiple of 4 and 10?

Explanation:

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Question (14)

Two children start clapping after every 6 seconds and 9 seconds respectively. They clap together now. After how many seconds will they clap together again?

Explanation:

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Question (15)

Find the LCM of 21 and 28.

Explanation:

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Question (16)

Which of the following is NOT a common multiple of 6 and 9?

Explanation:

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Question (17)

The prime factorisations of two numbers are: 24 = 2³ × 3 30 = 2 × 3 × 5 The LCM is:

Explanation:

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Question (18)

Find the LCM of 15, 20 and 30.

Explanation:

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Question (19)

A machine starts automatically every 14 minutes, while another starts every 21 minutes. If both start together now, after how many minutes will they start together again?

Explanation:

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Question (20)

Which statement about the Lowest Common Multiple (LCM) is true?

Explanation:

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