If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

A man died, leaving $10,000,000 for his widow, 5 sons and 4 daughters. Each daughter received an equal amount, each son received twice as much as a daughter, and the widow received three times as much as a son.

How much did the widow receive?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

How do you go from 98 to 720 using just one letter?

John can place six large boxes or nine small boxes into a carton.

Can you find out in how many cartons can he place sixty-six boxes in total?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211