To help get the brain cells firing. Not hard but require a bit of thought.

Problem 1: A man saves his kingdom from disaster and is brought before the king to be rewarded. The king says, "Name your reward, my good man, and I shall grant it." The man walks over to the king's chessboard and places a single grain of rice on a corner square. He then says, "If you would, sire, double the amount on each succeeding square so that the second square shall have two grains and the third shall have four grains and the fourth shall have eight and so on until all the squares are filled in." The king says, "Consider it done!"

Did the king make a wise decision? How much rice will the king require to fulfill the request?

Problem 2: Two witches are mixing a brew in a cauldron when the recipe calls for exactly 4 pints of yak sweat. They have a bucketful of yak sweat but no 4-pint measure. They have a pitcher that hold exactly 5 pints and a pot that holds exactly 3.

How can they use these to measure out the required 4 pints?

Problem 3: Millie and Geraldine are tending their flowers. One vase holds 5-petal primroses and 8-petal celandines. Millie counts all the petals and says, "Thirty-nine! Exactly my age!" Then she counts the flowers and says, "Exactly your age, Geraldine!"

How old is Geraldine?

Problem 4: Which 2-digit number is one more than a square and one less than a cube?

Problem 5: Which 3-digit number is made of consecutive digits and is two less than a cube but two more than a square?