TI -82 Manual Book page 257

Replacing the Batteries
1. Turn off the calculator. Replace the slide cover over the keyboard to
avoid inadvertently turning on the calculator. Turn the back of the
calculator toward you.
2. Hold the calculator upright. Place your thumb on the oval indentation
on the battery cover. Push down and toward you to slide the cover
about ¼ inch (6 mm). Lift off the cover to expose the battery
compartment.
Note: To avoid loss of information stored in memory, you must
turn off the calculator. Do not remove the AAA batteries and
the lithium battery simultaneously.
3. Replace all four AAA alkaline batteries at the same time. Or, replace the
lithium battery.
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To replace the AAA alkaline batteries, remove all four discharged
AAA batteries and install new ones according to the polarity
(+ and N) diagrams in the battery compartment.
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To remove the lithium battery, place your index finger on the
battery. Insert the tip of a ball-point pen (or similar instrument)
under the battery at the small opening provided in the battery
compartment. Carefully pry the battery upward, holding it with your
thumb and finger. (There is a spring that pushes against the
underside of the battery.)
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Install the new battery, + side up, by inserting the battery and gently
snapping it in with your finger. Use a CR1616 or CR1620 (or
equivalent) lithium battery.
4. Replace the battery compartment cover. Turn the calculator on and
adjust the display contrast, if necessary (step 1; page B . 4).
Reference Information B-3