What is the HCF of 16, 72 and 28 ?

Two numbers are in the ratio 3 : 4. Their LCM is 84 . The greater number is: 

If the students of a class can be grouped exactly into 6 or 8 or 10, then the minimum number of students in the class must be. 

HCF and LCM of two numbers are 7 and 140 respectively. If the numbers are between 20 and 45, the sum of the numbers is: 

What is the LCM (least common multiple) of 57 and   93?

The least number, which when divided by 4, 5 and 6 leaves remainder 1, 2 and 3 respectively is:

Find the HCF of 3341 and 3328.

Find the LCM of the fractions $${2\over 5}$$, $${3\over 7}$$ and $${4\over 9}$$