Tag: hcf-lcm

Questions Related to hcf-lcm

The G.C.D. of $1.08$, $0.36$ and $0.9$ is:

  1. $0.03$

  2. $0.9$

  3. $0.18$

  4. $0.108$


Correct Option: C
Explanation:

Given numbers are $1.08$, $0.36$ and $0.90$.

H.C.F. of $108$, $36$ and $90$ is $18$,
$\therefore$ H.C.F. of given numbers $= 0.18$.

Three number are in the ratio of $3 : 4 : 5$ and their L.C.M. is $2400$. Their H.C.F. is:

  1. $40$

  2. $80$

  3. $120$

  4. $200$


Correct Option: A
Explanation:

Let the numbers be $3x$, $4x$ and $5x$.
Then, their L.C.M. $= 60x$.
So, $60x = 2400$ or $x = 40$.
$\therefore $ The numbers are $\left( 3\times 40 \right) $, $\left( 4\times 40 \right) $ and $\left( 5\times 40 \right) $.
Hence, required H.C.F. $= 40$.

The H.C.F. of $\dfrac { 9 }{ 10 }$, $\dfrac { 12 }{ 25 }$, $\dfrac { 18 }{ 35 }$ and $\dfrac { 21 }{ 40 } $ is:

  1. $\dfrac { 3 }{ 5 } $

  2. $\dfrac { 252 }{ 5 } $

  3. $\dfrac { 3 }{ 1400 } $

  4. $\dfrac { 63 }{ 700 } $


Correct Option: C
Explanation:

Required H.C.F. $=\dfrac { H.C.F.\quad of\quad 9,12,18,21 }{ L.C.M.\quad of\quad 10,25,35,40 } = \dfrac { 3 }{ 1400 } $

What is the HCF of $3.0, 1.2$ and $0.06$?

  1. $0.6$

  2. $0.06$

  3. $6.0$

  4. $6.06$


Correct Option: B
Explanation:

The given terms are $\dfrac {3}{1}, \dfrac {6}{5}$ and $\dfrac {3}{50}$.
H.C.F. of these terms $= \dfrac {\text{H.C.F. of}\ 3, 6, 3}{\text{L.C.M. of}\ 1, 5, 50}$
$= \dfrac {3}{50} = 0.06$

What is the HCF of the polynomials $x^{4} - 3x + 2, x^{3} - 3x^{2} + 3x - 1$ and $x^{4} - 1$?

  1. $x - 1$

  2. $x + 2$

  3. $x^{2} - 1$

  4. None of the above


Correct Option: A
Explanation:

$x^{4} - 3x + 2 = x^{4} - x^{3} + x^{3} - x^{2} + x^{2} - x - 2x + 2$
$= x^{3} (x - 1) + x^{2} (x - 1) + x(x - 1) - 2(x - 1)$
$= (x - 1) [x^{3} + x^{2} + x - 2]$
$x^{3} - 3x^{2} + 3x - 1 = (x - 1)^{3}$
$x^{4} - 1 = (x - 1) (x + 1) (x^{2} + 1)$
$HCF = x - 1$

The G.C.D. of $5xy$ and $28ab$ is

  1. $140\ xyab$

  2. Cannot be determined

  3. $1$

  4. $0$


Correct Option: C
Explanation:

$5xy = 1*5*x*y$
$28ab = 1*7*2*2*a*b$
G.C.D = $1$

Find $HCF$ by finding factors:
$16$ and $56$.

  1. $6$

  2. $18$

  3. $8$

  4. $9$


Correct Option: C
Explanation:
Factorization of the following.
$16 = 2 \times 2 \times 2 \times 2$
$56 = 2 \times 2 \times 2 \times 7$
Since, the common factor is $2,2,8$,this implies that
$H.C.F = 2 \times 2 \times 2$
           $=8$
Hence,the correct option $C$.

Find HCF by using prime factor method:
$54, 81$ and $99$.

  1. $8$

  2. $9$

  3. $10$

  4. $11$


Correct Option: B
Explanation:
Factorization of the following.
$54 = 2 \times 3 \times 3 \times 3$
$81 = 3 \times 3 \times 3 \times 3$
$99 = 3 \times 3 \times 11$
Since, the common factor is $3 \times 3$,this implies that
$H.C.F = 3 \times 3$
Hence,the correct option $B$.

HCF of two or more prime numbers is equals to its ___________.

  1. $24$.

  2. $2$.

  3. $4$.

  4. $1$.


Correct Option: D
Explanation:

We know that

$H.C.F$ of two or more  prime Number is equal to its$ =1$.

Find $HCF$ by finding factors:
$75, 79$ and $89$.

  1. $2$

  2. $3$

  3. $1$

  4. $4$


Correct Option: C
Explanation:
Factorization of the following 
$75 = 5 \times 5 \times 3\times 1$
$79=1 \times 79$
$89 = 1 \times 89$
Since, the common factor is $1$ this implies that
$HCF = 1$

Hence, the correct option is $C$