Tag: lowest common multiple (l.c.m.)

Questions Related to lowest common multiple (l.c.m.)

Common factors of $9$ and $36$ are

  1. $1,3,9$

  2. $1,4,3,5,9$

  3. $1,4,5$

  4. none of these


Correct Option: A
Explanation:

Factors of $ 9 = 1, 3, 9 $
Factors of $ 36 = 1, 3, 4, 6, 9, 12, 36 $

Common factors are $ 1, 3, 9 $

Two containers have $950$ litres and $570$ litres of petrol. Find the maximum capacity of a container which can measure the petrol of either contianer in exact number of times?

  1. $190$ litres

  2. $280$ litres

  3. $380$ litres

  4. $270$ litres


Correct Option: A
Explanation:

Common factor of 950 and 570 is 190 , So A is the Correct answer

H.C.F. of 25, 75, 100 is

  1. 15

  2. 25

  3. 5

  4. 100


Correct Option: B
Explanation:

Factors of 25 = 1, 5 and 25.
Factors of 75 = 1,3,5,15,25 and 75.
Factors of 100 = 1,2,4,5,10,20,25,50 and 100
Therefore, common factor of 25,75 and 100 = 1,5,25.
H.C.F of 25,75 and 100 = 25.
Option B is correct.

The HCF of $3^5, 3^9$, and $3^{14}$ is

  1. $3^5$

  2. $3^9$

  3. $3^{14}$

  4. $3^{21}$


Correct Option: A
Explanation:

To  find  the  Highest  Common  Factor  (HCF)  of  two  or  more  numbers, 
find  prime  factors  of  the  numbers , and  then  identify  the  common  prime  factors.
Then  the  HCF  is  the  product  of  the  common  prime  factors.
$3^{5}= 1 \times 3^{5}$
$3^{9} = 1 \times 3^{5} \times 3^{4}$
$3^{14} = 1 \times 3^{5} \times 3^{9}$
Hence the HCF is $ 3^{5}.$
Another  method  to  find  the  answer  is  to find  the  largest  divisor  of all  three  numbers,
 which  is $ 3^{5} $

Which of the following numbers has exactly 4 factors?

  1. $16$

  2. $14$

  3. $18$

  4. None of these


Correct Option: B
Explanation:

(A) Factors of 16 are $1, 2, 4, 8, 16$
(B) Factors of 14 are $1, 2, 7, 14$
(C) Factors of  18 are $1, 2, 3, 6, 9, 18$

Find the common factors of the given terms:

$6 abc, 24ab^2, 12 a^2b$

  1. $6a^2b$

  2. $6ab^2$

  3. $6ab$

  4. $6$


Correct Option: C
Explanation:

$6 abc$, $24ab^2$, $12 a^2b$
The factors of $6abc=2\times 3\times a\times b\times c$
The factors of $24ab^2=2\times 2\times 2\times 3\times a\times b\times b$
The factors of $12 a^2b=2\times 2\times 3\times a\times a\times b$
The common factors are $2\times 3\times a\times b=6ab$

Find the common factors of the given terms:

$2x, 3x^2, 4$

  1. $3$

  2. $2$

  3. $6$

  4. $1$


Correct Option: D
Explanation:

$2x$, $3x^2$, $4$
The factors of $2x=2\times x$
The factors of $3x^2=3\times x\times x$
The factors of $4=2\times 2$
Thus, the common factors is $1$

Find the common factors of the given terms:

$2y, 22xy$

  1. $2y$

  2. $y$

  3. $11y$

  4. $2$


Correct Option: A
Explanation:

$2y$,$22xy$
The factors of $2y=2\times y$
The factors of $22xy=2\times 11\times x\times y$
Thus, the common factors are $2\times y=2y$

Find the common factors of the given terms:

$16 x^3, 4x^2, 32x$

  1. $x$

  2. $16$

  3. $4x$

  4. $32$


Correct Option: C
Explanation:

$16 x^3$,  $4x^2$, $32x$
The factors of $16 x^3=2\times 2\times 2\times 2\times x\times x\times x$
The factors of $4x^2=2\times 2 \times x\times x$
The factors of $32x=2\times 2\times 2\times 2\times 2\times x$
The common factors are $2\times 2 \times x=4x$

The expression $x^{2} - x - 30$ is positive for

  1. no value of $x$

  2. all values of $x$ between - 5 and 6

  3. all $x$

  4. $x > 6$ or $x < - 5$


Correct Option: D