Four different sets of objects contain 3, 5, 6, and 8 objects, respectively. How many unique combinations can be formed by picking one object from each set?

Here is the reasoning. Pick one object from the first set. There are three possibilities. Pick a second object from the second set. There are 5 possibilities. So, there are 3 x 5 = 15 possibilities for choosing from the first two sets. Continue in this way. There are a total of 3 x 5 x 6 x 8 = 720 combinations, not counting the order in which they are picked. The answer is 720.