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

Q 1 - 10951168 when expressed in simplest form is?

A - 1516

B - 1316

C - 1726

D - 2526

Answer : A

Explanation

Q 2 - What will be the least number which when doubled will be exactly divisible by 12, 18,21 and 30?

A - 630

B - 196

C - 1260

D - 2520

Answer : A

Explanation

L.C.M of 12, 18, 21, 30 = 2 x 3 x 2 x 3 x 7 x 5 = 1260.
Required number =(12602) = 630

Q 3 - The least number, which when divided by 12,15,20 and 54 leaves in each case a remainder of 8, is?

A - 500

B - 548

C - 544

D - 536

Answer : B

Explanation

Required number = (L.C.M of 12, 15, 20, 54) + 8 = 540 + 8 = 548.

Q 4 - The product of two numbers is 2028 and their H.C.F is 13. The number of such pairs is?

A - 2

B - 1

C - 3

D - 4

Answer : A

Explanation

Let the numbers be 13a and 13b. then 13a x 13b = 2028
a x b = 12. 
 Now co-primes with product 12 are (1, 12) and (3, 4).
So, the required numbers are (13 x 1, 13 x 12) and (13 x 3, 13 x 4)
clearly, there are 2 such pairs.

Q 5 - The H.C.F and L.C.M of two numbers are 11 and 385 respectively. If one number lies between 75 and 125, then the number is?

A - 88

B - 99

C - 110

D - 77

Answer : D

Explanation

Product of numbers = 11 x 385. 
 let the numbers be 11a and 11b. then 11a x 11b = (4235) = ab = 35
Now co-primes with product 35 are (1, 35) (5, 7).
So the numbers are (11 x 1, 11 x 35) and (11 x 5, 11 x 7).
Since one number lies between 75 and 125 the suitable pair is (55, 77).
Required number = 77.

Q 6 - If the L.C.M of A and B is C, their H.C.F. is

A - C/AB

B - ABC

C - (A+B)/C

D - AB/C

Answer : D

Explanation

HCF*LCM=A*B
⇒HCF=(A*B)/LCM=AB/C

Q 7 - Find the H.C.F. of 1296 and 2400

A - 96

B - 48

C - 24

D - 12

Answer : B

Explanation

1296=24x34 and 2400=25x3x52
HCF=24x3=48

Q 8 - If two numbers are greater than 13 and the H.C.F of two numbers be 13, L.C.M 273, then the sum of the numbers is:

A - 286

B - 130

C - 288

D - 290

Answer : B

Explanation

Let the number be 13 a and 13 b, where a and b are co-primes.
Then, 13a * 13b=   (13* 273)  ⇒ab= 21
Two co-primes with product 21are 3 and 7.
∴ numbers are (13*3, 13*7) i.e , 39 and 91.
Their sum = (39+91) = 130

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 divisor of 210, 315, 147 and 168.

A - 3

B - 7

C - 21

D - 44

Answer : C

Explanation

210  = 2*3*5*7,   315 =3*5*3*7 , 147 = 7*7*3  , 168 = 2*2*2*3*7
Required number = H.C.F of given  numbers=  (3*7) =21


aptitude_hcf_lcm.htm

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