TI-83 & TI-84 Calculator Quirks There is a potentially fatal flaw to entering exponential numbers on the TI-83/TI-84 calculator (and perhaps others too) DO NOT use the 10x key or the ^ key. EVER. You can type in the numbers in what seems like the correct fashion, but the calculator won't interpret your keystrokes the way that you think that it will. For example: Let's say we want to calculate the frequency of sodium light which has a wavelength of 539 nanometers. We know that the speed of light is related to the frequency and wavelength of light by: c = νλ So solving or frequency we have: ν = c/λ so ν = (3.00 x 108 m/s)/(539 x 109 m) if you type in: 3.00 * 10 ^ 8 / 539 * 10 ^ 9 the answer you get is 5.567862709 x 1014 WHICH IS CLEARLY NOT CORRECT (click here to see why) So From now on YOU MUST ABSOLUTELY POSITIVELY USE THE {EE} Key 3.00 {2nd} {EE} 8 / 539 {2nd} {EE} 9 which produces the much more meaningful (and accurate) answer: 5.57 E -4 (after sig figizing) or 5.57 x 10-4 Which is much, much more reasonable TRY IT! (You'll like it or maybe not) But USE IT ALWAYS ======================================================== Here's why it gets weird: Consider again our equation: ν = (3.00 x 108 m/s)/(539 x 109 m) and how we might incorrectly enter that into our calculator: 3.00 * 10 ^ 8 / 539 * 10 ^ 9 Here's how our calculator interprets that input: 3 x 108 / 539 x 109 or in written words: the speed of light divided by 539 multiplied by a billion! Which is clearly not what we want to do!