
1 
Find the HCF of 2/3, 8/9, 64/81 and 10/27.


A. 
2/3 

B. 
2/81 

C. 
160/3 

D. 
160/81 
See Answer & Explanation
Lets Discuss
Correct answer is : B
Explanation The HCF of a fractional number is :
HCF of numerators/ LCM of denominators.
2 
Find the LCM of 2/3, 3/5, 4/7, 9/13. 

A. 
36 

B. 
1/36 

C. 
1/1365 

D. 
12/455 
See Answer & Explanation
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Correct answer is : A
Explanation LCM of a fraction = LCM of numerators / HCF of denominators.
3 
The HCF of 1.75 , 5.6, 7 is 

A. 
0.07 

B. 
0.7 

C. 
3.5 

D. 
0.35 
See Answer & Explanation
Lets Discuss
Correct answer is : D
Explanation To solve such questions which has decimals, first bring all the decimals to common decimal places in the following way:
1.75 , 5.6, 7
Steps:
Step 1.
The number with highest number of decimal places is : 1.75 (2 digits after decimal).
So bringing all the other options to 2 decimal places.
1.75 remains 1.75
5.6 becomes 5.60
7 becomes 7.00
Step 2.
Now take the numbers without decimal places i.e multiply each number by 100.
We get : 175, 560,700.
Step 3.
Find the HCF of these numbers and divide it by 100 (because we multiplied the numbers by 100).
175= 5x5x7
560= 2x2x2x2x7x5
700= 2x2x5x5x7
Here 5x7 is the common factor in all the 3 numbers = 35
Dividing it by 100 we get 0.35 as the HCF..
4 
The LCM of 3, 2.7, 0.09 is : 

A. 
2.7 

B. 
0.27 

C. 
0.027 

D. 
27 
See Answer & Explanation
Lets Discuss
Correct answer is : D
Explanation To solve such questions which has decimals, first bring all the decimals to common decimal places in the following way:
3, 2.7, 0.09
Steps:
Step 1.
The number with highest number of decimal places is : 0.09 (2 digits after decimal).
So bringing all the other options to 2 decimal places.
3 becomes 3.00
2.7 become 2.70
0.09 remains 0.09
Step 2.
Now take the numbers without decimal places i.e multiply each number by 100.
We get : 300, 270, 9
Step 3.
Find the LCM of these numbers and divide it by 100 (because we multiplied the numbers by 100).
300 = 2x2x5x5x3
270=3x3x3x2x5
9= 3x3
Raise each of the prime factors to its highest power in each number.
2^{2} x 5^{2} x 3^{3} = 2700
Dividing by 100 we get 27.
5 
Three numbers are in the ratio 2:3:5 , and their HCF is 12. Find the numbers. 

A. 
12,18,30 

B. 
24, 36,60 

C. 
20,30,50 

D. 
8,12,20 
See Answer & Explanation
Lets Discuss
Correct answer is : B
Explanation The numbers can be written as 2x : 3x : 5x. And since HCF is the highest common factor. x = HCF.
So, the numbers are: 2x12, 3x12, 5x12 = 24,36,60


