There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

What does it mean?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

Use the digits from 1 up to 9 and make 100.

Follow the rules.
=> Each digit should be used only once.
=> You can only use addition.
=> For making a number, two single digits can be combined (for example, 4 and 2 can be combined to form 42 or 24)
=> A fraction can also be made by combining the two single digits (for example, 4 and 2 can be combined to form 4/2 or 2/4)

Question: how can we do this?

How can you take 2 from 5 and leave 4?

You have two buckets - one holds exactly 5 gallons and the other 3 gallons. How can you measure 4 gallons of water into the 5 gallon bucket?

(Assume you have an unlimited supply of water and that there are no measurement markings of any kind on the buckets.)