I need calculator help ASAP!!!

<p>I'm taking a stats/gemometry class right now (We're in the stats part right now), and am having problems with my calculator. The numbers I'm dealing with are simply too large for my TI-84 to handle, and it's giving me a major headache! Would a TI-89 take bigger numbers? If it does, would it be worth it to upgrade to the TI-89 (I still have another math class left to take, either advanced math for teachers or stats.), or should I just tough it out with my 84? I have a test on Monday, so I'll need it by then!</p>

<p>As it turns out, most of it's problems were the fact that I was keying in the equations rather than using the built in functions. I'm going to change the batteries in it, and go from there.</p>

<p>Yeah, I was thinking that if the numbers are too big for the calculator... you might be doing something wrong.</p>

<p>There was one problem that even a math major friend of mine kept getting over 3 trillion for the answer of. It was the right formula (30!/[(3!)(30-3)!]), but not using the built in function it would give you back a HUGE answer. The 83 and 84 are just really picky about certain things!</p>

<p>That's because given user input, the calculator doesn't know it can immediately cancel terms. Given 30!/(27!3!), it would computer the numerator and then compute the denominator and then divide them. But since the calculator only has something like 32 bits of memory, it can only accurately handle numbers below 2^32. If you put in something bigger than that, it ignores all the binary digits in places bigger than 32. So if you only had 3 bits (meaning you could only handle numbers 0-7), and you did a computation that should be eleven (1011, aka 8+2+1 in binary), the calculator could only store the first 3 bits (basically it has nothing to keep track of 8s), and so it would think the answer is three (011=2+1 in binary). It's called a memory overflow error, and I will have to learn how to deal with this crap when I start using c++ next semester. If you use the built-in 30 nCr 3, it knows that the computation reduces down to 30<em>29</em>28/3!, which involves numbers it can handle.</p>

<p>Funnily enough, my $15 Casio fx-82MS can handle 30!/(27!3!) just fine.</p>

<p>It needed the batteries changed! I swapped them out and it started giving me the same answers every time, and not being so random! I think it was on the original set of batteries, which means that this was the 4th collegiate math they were being used for.</p>