H.C.F & L.C.M. - Online Quiz


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Following quiz provides Multiple Choice Questions (MCQs) related to H.C.F & L.C.M.. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Questions and Answers

Answer : D

Explanation

Making the same number of decimal places, the given numbers are 0.63, 1.05 and 2.10.
without decimal places, these numbers are 63, 105, and 210
Now, H.C.F of 63, 105 and 210 is 21 so H.C.F of 0.63, 1.05 and 2.1 is 0.21 
 L.C.M of 63, 105 and 210 is 630 so L.C.M of 0.63, 1.05 and 2.1 is 6.30

Q 2 - Which of the following fractions is the largest?

A - 78

B - 1316

C - 3140

D - 6380

Answer : A

Explanation

L.C.M of 8, 16, 40 and 80 = 80
78 = 7080; 1316 = 6580; 3140 = 6280
Since 7080 > 6380 > 6580 > 6280
78 > 6380 > 1316 > 3140
S0, 78 is the largest.

Q 3 - The sum of two numbers is 528 and their H.C.F is 33. The number of pairs of numbers satisfying the above conditions is?

A - 4

B - 6

C - 8

D - 12

Answer : A

Explanation

Let the numbers be 33a and 33b. then 33a + 33b = 528
a + b = 16.
Now, co-primes with product 16 are (1,15) (3,13) (5,11) and (7,9)
So, the required numbers are (33 x 1, 33 x 15) (33 x 3, 33 x 13) (33 x 5, 33 x 11) (33 x 7, 33 x 9)
the number of such pairs is 4.

Q 4 - The L.C.M of two numbers is 48. The numbers are in the ratio 2:3. The sum of the number is?

A - 40

B - 45

C - 50

D - 60

Answer : A

Explanation

Let the numbers be 2z, and 3z. then their L.C.M = 6z 
 So, 6z = 48 or z = 8.
Therefore the numbers are 16 and 24
Hence the required sum = 40.

Q 5 - The H.C.F of two numbers is 8. Which of the following can never be their L.C.M?

A - 60

B - 24

C - 48

D - 56

Answer : A

Explanation

H.C.F of two numbers divide their L.C.M exactly. Clearly 8 is not a factor of 60.

Q 6 - The L.C.M. of two numbers is 72. Their H.C.F. is 12. If one number is 12, the other is

A - 24

B - 28

C - 32

D - 36

Answer : D

Explanation

Let the other number be X
HCF*LCM=Product of two numbers
12*72=24*X
⇒X=(12*72)/24=36

Q 7 - The G.C.D. of 0.93, 0.60 and 0.75 is:

A - 0.03

B - 0.06

C - 0.09

D - 0.12

Answer : A

Explanation

Given numbers are 0.93, 0.60 and 0.75.   H.C.F. of 93, 60 & 75 is 3.
 H.C.F. of given numbers = 0.03

Q 8 - Sum of two numbers is 60 and their H.C.F and L.C.M are 12 and 72 respectively. One of the numbers is:

A - 12

B - 24

C - 60

D - 72

Answer : B

Explanation

Let the numbers be  12 a and 12 b, where a and b are co primes.
Then, 12 a *12 b = 12 *72  ⇒ ab= 6
co-primes with product 6 are a = 2, b= 3
∴ numbers are (12*2, 12*3 ) i.e  24 and 36

Q 9 - Having two numbers in the ratio 5:7 and their L.C.M as 315, then their product is:

A - 2358

B - 2385

C - 2538

D - 2835

Answer : A

Explanation

Let the two numbers be 5x and 7x . Then, their L.C.M is  35 x.
35x =  315    ⇒   x= 9
∴ The numbers are 45 and 63 and their product is 2835.

Q 10 - Find the largest fraction among the following:

A - 7/8

B - 13/16

C - 31/40

D - 63/80

Answer : A

Explanation

L.C.M of 8, 16,40 , 80 is 80.
7/8  =  (7/8 *10/10 ) = 70/80  , 13/16 = (13/16*5/5)=  65/80 ,31/40 = (31/40* 2/2 )= 62/80,63/80
Clearly ,70/80 > 65/80 >63/80 >62/80 . Hence, 7/8 is the largest.

aptitude_hcf_lcm.htm
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