Solution 15040: Specifying Infinity in a Calculation Using the TI-83 Family, TI-84 Plus Family and TI-Nspire™ Handheld in TI-84 Plus Mode.
How do I specify infinity in a calculation using the TI-83 family, TI-84 Plus family and TI-Nspire in TI-84 Plus mode?
Both the TI-83 family and TI-84 Plus family graphing calculators do not include an infinity symbol. An alternate method for inputting values for either positive or negative infinity can be used.
Example - To specify positive infinity, input 1E99. To specify negative infinity, input -1E99.
The "E" symbol is short for scientific notation and can be accessed by pressing [2nd] [ , ]. -1E99 can be interpreted as "negative one times 10 to the ninety-ninth power".
Please see the TI-83 family and TI-84 Plus family guidebooks for additional information.
TI-Nspire handheld in TI-84 Plus mode users may refer to the TI-84 Plus family guidebook.