If you're talking about the key and and LED lights above the calculator pad, you use those to test and see if the light your keyboard is getting is enough to keep it going. Push the key with the circle with rays coming off of it and either the green LED to the right lights up briefly, meaning it's getting enough light, or the red LED lights up briefly, meaning not enough light. I only check it once in a while if the room is getting darker, etc... like in the evening. Then I just turn on my desk lamp and continue.
9 years ago
by
Posted by:
planetwalt
from
Phoenix, AZ