Puzzle No. 021
Picarats: 30


A man has been prescribed 10 pills. Starting today, he must take one pill a day, but because the concentration of the medicine is different in each pill, he must take them in a specific order. Since the pills all look the same, the man has decided to write number on each pill to help him remember the order he needs to take them in.

How many pills does he have to number if he wants to keep track of the order?














Hint One: If the man wants to indicate the order in which he needs to take his pills, he just needs to write a number on each of the 10 pills. While that's true, the bare minimum of numbers he needs to write is fewer than 10. Think about how he can accomplish this.

Hint Two: When you have two visually identical items, you only need to mark one of them. Therefore, you don't need to mark each pill to tell them apart.

Hint Three: Keep in mind that the man must start taking his pills today. In fact, he's going to start by taking the pill right in front of him.

If that's the case, does he really need to mark which pill he's going to take today?

Solution:














Good job!

Since the man has to start taking his medicine today, the first thing he should do is take today's pill. Next, he should label the pills for days two through nine. If he does this, he shouldn't have to label the pill for the last day; it will be the only one withoug a label.

He only needs to label eight pills.