CoCubes HCF and LCM Question and Answers Quiz-1

Let the numbers 13a and 13b.

Then, 13a x 13b = 2028

=>ab = 12.

Now, the co-primes with product 12 are (1, 12) and (3, 4).

[Note: Two integers a and b are said to be coprime or relatively prime if they have no common positive factor other than 1 or, equivalently, if their greatest common divisor is 1 ]

So, the required numbers are (13 x 1, 13 x 12) and (13 x 3, 13 x 4).

Clearly, there are 2 such pairs.

Required number = H.C.F. of (1657 - 6) and (2037 - 5)

= H.C.F. of 1651 and 2032 = 127.

Let the numbers be 3x, 4x and 5x.



Then, their L.C.M. = 60x.



So, 60x = 2400 or x = 40.



The numbers are (3 x 40), (4 x 40) and (5 x 40).



Hence, required H.C.F. = 40.

HCF of two prime numbers = 1
∴ Product of numbers = 117 (Their LCM)
117 = 13\times 9 where 13 & 9 are co-prime.
LCM (13, 9) = 117.
Hence option [D] is correct answer.

Let the required numbers be 33a and 33b.



Then 33a +33b= 528 => a+b = 16.



Now, co-primes with sum 16 are (1,15) , (3,13) , (5,11) and (7,9).



Therefore, 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

3.78 meters =378 cm = 2 × 3 × 3 × 3 × 7

5.25 meters=525 cm = 5 × 5 × 3 × 7

Hence common factors are 3 and 7

Hence LCM = 3 × 7 = 21

Hence largest size of square tiles that can be paved exactly with square tiles is 21 cm

L.C.M. of 6, 9, 15 and 18 is 90.



Let required number be 90k + 4, which is multiple of 7.



Least value of k for which (90k + 4) is divisible by 7 is k = 4.



=>Required number = (90 x 4) + 4 = 364.

Product of numbers = 11 x 385 = 4235



Let the numbers be 11a and 11b . Then , 11a x 11b = 4235 => ab = 35



Now, co-primes with product 35 are (1,35) and (5,7)



So, the numbers are ( 11 x 1, 11 x 35) and (11 x 5, 11 x 7)



Since one number lies 75 and 125, the suitable pair is (55,77)



Hence , required number = 77

Required Number = (L.C.M of 12, 16, 18,21,28)+7

= 1008 + 7

= 1015

Given numbers are 1.08 , 0.36 and 0.90

H.C.F of 108, 36 and 90 is 18 [ ∵ G.C.D is nothing but H.C.F]

Therefore, H.C.F of given numbers = 0.18