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

Quiz

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.

Q 1 - Find the lowest common multiple of 24, 36 and 40?

Answer : B

Explanation

L.C.M = 2 x 2 x 2 x 3 x 3 x 5 = 360

Q 2 - The G.C.D of 1.08, 0.36 and 0.9 is?

Answer : B

Explanation

Given numbers are 1.08, 0.36 and 0.9. H.C.F of 108, 36 and 90 is 18.
H.C.F of given numbers is 0.18.

Q 3 - Find the highest common factor of 36 and 84.

Answer : D

Explanation

36 = 2² x 3² 84 = 2² x 3 x 7.
Therefore H.C.F = 2² x 3 = 12.

Q 4 - Product of the two co-prime numbers is 117. Their L.C.M should be?

Answer : D

Explanation

H.C.F of Co-prime number is 1. So, L.C.M = ¹¹⁷⁄₁ = 117

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

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 - Find the L.C.M. of 2/3, 2/5 and 2/7.

Answer : A

Explanation

L.C.M. of given fractions =  (L.C.M.of numerators)/(H.C.F.of denominators)=2/1=2
(L.C.M.of numerators = 2  H.C.F.of denominators =1)

Q 7 - H.C.F. of two numbers is 12 and their L.C.M is 72. If the difference between the numbers is 24, their sum is

Answer : C

Explanation

Let the numbers be X & Y
HCF*LCM=Product of two numbers =XY=12x72=864
XY=864 -------- (1)
Given X-Y=24   -------- (2)
On solving 1 & 2 we get X=12 Y=36
Their sum = 12+36=48

Q 8 - H.C.F and L.C.M of two 3-digit numbers are 29 and 4147 respectively. What is the sum of the numbers?

Answer : C

Explanation

Let the numbers be 29a and 29 b , where a and b  are co-primes.
Then, 29 a * 29 b + 29*147 ⇒ ab + (29*4147)/(29*29)= 143
co-primes with product 143 are 11  and 13.
∴ numbers are (29*11,   29* 13) i.e ,  319, 377
Their sum = (319+377)= 696

Q 9 - H.C.F and L.C.F of two numbers x and y are 3 and 105 respectively. If x+y=36 then figure out 1/x + 1/y.

Answer : D

Explanation

We have X *y =3 *105 ⇒ xy = 315
∴  x+y/xy =36/315  = 4/35 ⇒ 1/y+1/x = 4/35 ⇒ 1/x+1/y = 4/35.

Q 10 - The L.C.F of two prime numbers x and y is 161. If x > y then the value of (3y- x) is:

Answer : A

Explanation

161 = 7*23  , so, X = 23 and y= 7
∴ (3y-x)=  (3*7-23 )= -2

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