Length (feet, meters)
Area (square feet, square meters)
Mass and Weight (ounces,grams)
Liquid Volume (pints, liters)
Temperature (Fahrenheit, Celsius
Each field that displays an answer is made "read-only" so the user can't type over the calculated answer. To make a field read-only, make it lose the focus (blur()) as soon as it gets the focus (onfocus).