Challenge Level

Find the frequency distribution for ordinary English, and use it to help you crack the code.

Challenge Level

Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...

Challenge Level

A monkey with peaches, keeps a fraction of them each day, gives the rest away, and then eats one. How long can his peaches last?

Challenge Level

Can you find a cuboid that has a surface area of exactly 100 square units. Is there more than one? Can you find them all?