You have a horrible disease but thankfully there is a medicine for it. Everyday you must take one pill called Batz and one pill called Scatz. On the very first day, you pour one Batz in your hand then you pour two Scatz in your hand by accident! These pills are identical and if you take too much or too little of either pill on any day you will die. You cannot get a refill or throw any pills away.
How can you still take the pills you have in your hand and live?
To do this you just have to get another Batz and cut all four pills in half taking a half from each pill. Do the same the next day and you will definitely get the right amount of each pill for the two days.