Problems on H.C.F and L.C.M - General Questions

Three bells toll at intervals of 12, 10, 2 minutes. If they toll together now, after how many minutes will they next toll together?

The H.C.F. of two numbers is 15 and their L.C.M. is 330. If one of the numbers is 165, what is the other?

Three bells toll at intervals of 15, 20, 10 minutes. If they toll together now, after how many minutes will they next toll together?

Find the L.C.M. of 30, 16 and 4.

What is the least number which, when divided by 20, 10, 4, leaves a remainder 1 in each case?