Fun Riddles

Question: How do you make the number one disappear by adding to it?

Question: A mirror for the famous, but informative to all.
I'll show you the world, but it may be a bit small.

What I am?

Question: How can you throw a ball 20 meters, and have it come back to you without hitting anything?

Question: What 3 positive numbers give the same result when multiplied and added together?

Question: Jack is taking a tour through a museum's American Presidents exhibit. The person leading the tour tells him "We have a picture of each presidency. Currently Barack Obama is the 43rd person to hold the office." But Jack quickly realizes that there are 44 pictures on the wall. But while walking through the exhibit he realizes why this is.

Why is there one too many photos?