I am white when I am dirty, and black when I am clean. What am I?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

How many times can you subtract the number 5 from 25?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

A man started to town with a fox, a goose, and a sack of corn. He came to a stream which he had to cross in a tiny boat. He could only take one across at a time. He could not leave the fox alone with the goose or the goose alone with the corn. How did he get them all safely over the stream?

How can you take 2 from 5 and leave 4?

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?

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?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?