LCM of two numbers is 504 and their HCF is 8. If one of the numbers is 72, find the other.

The product of two numbers i 5415. If the HCF of these numbers is 19, then the number of such pairs of natural numbers is __

The ratio of two numbers is 2:5 and their HCF is 12. Their LCM is __

The ratio of two numbers is 2:3 and their LCM is 60. Find their HCF.

Three numbers which are co-prime to each other are such that the product of first two is 323 and last two is 399. Find the sum of three numbers.