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

Find the greatest number that divides 83, 15, 51 leaving the same remainder in each case.

Find the L.C.M. of 8, 34 and 9.

Three bells toll at intervals of 4, 18, 8 minutes. If they toll together now, after how many minutes will they next toll together?

Three bells toll at intervals of 12, 4, 5 minutes. If they toll together now, after how many minutes will they next toll together?

What is the least number which, when divided by 4, 9, 18, leaves a remainder 2 in each case?