Introduction 9
To calculate the heat loss of the water heater, merely press the following keys in order.
 Keystrokes Display 15 ENTER 15.0000 Temperature difference. 30 30 _ Area of water heater (sq. ft.). × 450.0000 Intermediate answer. .47 .47 _ Coefficient of heat transfer. × 211.5000 Heat loss in Btu per hour.
Programming the Sample Problem
The water heater in the example loses about 212 Btu every hour at the 15-degree temperature difference. Suppose you decide to calculate the heat loss of the water at many temperature differences. You could calculate the heat loss manually for each temperature difference. Or an easier and faster method is to write a program that will calculate the heat loss for any temperature difference.
Now let’s write, load and run a program to do just that!
Writing the program. You have already written it! The program is the same series of keystrokes you executed to solve the problem manually. One additional instruction, a label, is used to define the beginning of the program.