Part 3: A suitcase has a combination lock with four wheels. Each wheel has ten digits, 0 through 9 How many different combinations are there? Assume that a thief can try one combination every second, and that the thief will get lucky after trying about half the combinations, how long will it take the thief to open the briefcase?

If each wheel of the briefcase lock has only eight digits: 0, 1, 2, 3, 4, 5, 6, 7; how many different combinations are there? How long will it take our thief to open the lock?

Part 4: Suppose that a lock like the one described above has only two numbers, 0 and 1, on the wheels, and there are four wheels. How many combinations are there? What happens if an additional wheel is added? How many combinations, and how long to "crack?"

In general, what does adding another wheel do to the number of combinations?

Part 5: Explain what, if anything, the previous two exercises have to do with encryption and what, if anything, you learned from them.

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