Math Riddles

Question: can you make an equation by using only the no.-4,4,4,4 whose answer will be 20.

Question: You need a room for your group. Each person needs 5 square feet of space. You have 25 people in your group, what is the smallest room you can use?

Question: Bobby's teacher gave him a math quiz. Every time he got an answer right, points would be taken away, so whoever had the most points, got the most questions wrong. Bobby's score was the highest, yet he still got the most questions correct out of the class. How is this possible?

Question: If 2=8, 3=27, 4=64, and 6=216, what does 9 equal?

Question: What exponents other than the same two numbers with the numbers one thru ten can be flipped and have the same answer?