This question demonstrates what can happen if you use rounded numerical results too soon. Always keep enough digits in intermediate calculations to arrive at a final answer with sufficient precision. Consider the following problem. Suppose you want to buy 100 pens. You can buy 100 pens at a 10% discount at one store where the price is $1.99 per pen. And you can also buy 100 pens at a 15% discount at another store where the price is $2.13 per pen. A) What is price per pen at the first store? B) What is the price per pen at the second store?
C) What is the total price difference for 100 pens?