What ’ s “ pi ” ?   That ’ s the ratio of the circumference of a circle to its diameter , I think .   I see . What is that ratio exactly ?   It ’ s approximately 3.14 , but the number continues forever . What ’ s the diameter of your circle ?   It ’ s 10 centimeters , so the circumference should be 31.4 centimeters .   Ok . My next problem is to convert 10000 british pounds into us dollars . What ’ s the exchange rate at the moment ?   According to the newspaper , the exchange rate is 1.85 dollars to the pound .   That means that 10.000 pounds will buy me 18.500 dollars .   What ’ s the next question .   Fractions . What ’ s a quarter and an eighth ? That ’ s three-eights . Easy . The next question is “ what are prime numbers ? ” .   I can help you there . Those are numbers that cannot be created by multiplying two whole numbers , apart from the number itself and 1 , together . 