5 bells ring at intervals of 56, 160, 24, 18, 40 seconds, respectively. If the bells ring together at 10 o'clock, when will they ring together again? How many times will they ring together in 840 minutes?
204 cola cans and 408 fruit juice cans need to be stacked in a school canteen. If each stack is to be of the same height and has to contain cans of the same type, find the greatest number of cans each stack can have.