They all get cut down.

Water.

10, take the first letter of each spelled out number:

One+Nine+Eight= ONE
Two+Eight+Nine= TEN

10, take the first letter of each spelled out number:

One+Nine+Eight= ONE
Two+Eight+Nine= TEN

He’s a barber.

50 pounds.

In the beginning it is 99 pounds water and 1 pound other stuff. At the end the 1 pound other stuff is 2 percent so the total weight is 50 pounds. 50 pounds – 1 pound other stuff = 49 pounds water. So 99 pounds – 49 pounds = 50 pounds water lost.

Here are the rules they can use to ensure they will all go free eventually:

The prisoners will choose one ‘leader’ and everybody else will be a follower. If you are a follower:

• If switch A is in the on position, toggle switch B.
• If switch A is off, you have not toggled switch A yet, and you have seen switch on during a previous visit; then toggle switch A. Otherwise toggle switch B.

If you are a leader:

• If switch A is off, turn it on.
• If switch A is on, turn it off. If you did not turn switch A on during their previous visit, increment the count of prisoners.

Once the leader increments the count to 23 they can yell, “Every prisoner has been here!” and all of them will be released.

Stop searching!

Barack Obama, his name was still Barack Obama in 1980.