Turn the calculator over so that the blue Texas Instruments logo is up.
Slide the blue case downward until it is completely removed from the calculator.
Turn the calculator over and locate the sliding latch on the back of the calculator.
At the same time, slide the latch to the right and pull the keypad downward. This should completely separate the keypad from the calculator.
Now that you have detached the keypad, gather the cotton swabs and rubbing alcohol.
Dampen a cotton swab by placing 1 to 3 drops of rubbing alcohol on the tip.
Use the moistened cotton swab and rub it around each button, in crevices, and anywhere on the keypad that may have dirt. Replace the swab as often as desired.