The ratio of HCF and LCM of two numbers a and b is 1:30 and the difference between the HCF and LCM is 493. Find the possible number of pairs of a and b.

The number between 4000 and 5000 that is divisible by each of 12, 18, 21 and 32 is 

The difference between the greatest and least prime numbers which are less than 100 is:

A number between 1000 and 2000 which when divided by 30, 36 and 80 gives a remainder 11 in each case is:

The smallest five digit number which is divisible by 12, 18 and 21 is:

The greatest four digit number which is exactly divisible by each one of the numbers 12, 18, 21 and 28.

If the least common multiple of two numbers, 1728 and K is 5184, then how many values of K are possible? 

A man buys 12 articles for Rs. 12 /- and sells them at the rate of Rs.1.25 per article. His gain percentage is: