LCM and HCF Problems Tips and Tricks
First learn the the formulas and how to find LCM and HCF on this page here.
Sum of two numbers is given and LCM and HCF is given. Find sum of reciprocals
Way to solve Type 1 Questions
Let numbers be a and b. So a + b is given.
You know LCM x HCF = product of two numbers i.e. a x b is also given
So 1/a + 1/b = (a + b)/(a x b)
Example. If the sum of two numbers is 55 and the H.C.F. and L.C.M of these numbers are 5 and 120 respectively, then the sum of the reciprocals of the numbers is equal to
with this direct formula answer is 55/(5×120) = 11/120
Now this question can be iterated. Where some times LCM, product and sum is given but not HCF or other permutations of the same.