Karandago's Full Review: Texas Instruments TI-89 Titanium Scientific Calcul...
I have had my TI 89 now for almost two years, and I love it to death. I think it would be best for my to start out naming my favorite features. It has THE number one feature I believe that a calculator could have which is a 30 operation memory. This means that when I hit 2 + 2 and it gives me 4 ten calculations later when I go.. Wait what was that 2 + 2 again I can just scroll up the screen and check... "Oh yea 4". Coming in a close second... or maybe it's a tie for first because they work together... is it formats things the way you would on paper. As these things together might not seem like the ultimate in calculator experiences I will now jump into an anecdote.
This calculator completely saved my life in chemistry. At the time we were just beginning learning dimensional analysis and stoicheometry, if you are not familiar with them don't worry just assume that they involve a lot of big calculations. I had a standard $20 scientific calculator and it worked fine except for the fact that when typing in the ten or twelve different values that I had written down on my paper I would often make a mistake and when I hit = I would end up with a value that was wrong... and as I had everything write on my paper and it was a error in typing on my calculator I didn't know this. I managed to fail several tests this way. I then got my TI 89, now a problem goes something like this... Write out calculations on paper... type into calculator, looking something like (25.3 * 3 * 1000 * 3 * 1 * 1) / (2 * 1 * 4 * 100 * 37.8), it would then format that as a fraction the parentheses on the left on top the parentheses on the right on the bottom, and I would just double check with the numbers on my paper to make sure I hadn't made an error. Combine this with the fact that I can then use this answer at any time (before I've done 30 more of these) in another calculation by hitting the ANS(1) key and suddenly larger multi step problems are a breeze. The 30 operation memory also came in handy here because if I make a mistake somewhere along the line and in the end I come up with some number that makes no sense I can just scroll back through my calculations and go, "Ok.. So it was there that I made a mistake. That should be a 2 not a 3", it has saved me many a time.
Now on to the other things it does... Quite frankly I often joke that it is smarter than I am. And as of yet I don't know how to use all of it's functions. I just this year learned how to use the alpha-numeric solver. I can just put in an equation 3x + 2 = 11, yes over simplified, and it'll tell me what x is. Now this might often seem like the easy way out and sometimes it has been, but it can also be extremely helpful for saving time because you can drop something like a quadratic equation in there and it'll tell you what x is, without going through all of the negative b plus or minus the square root of b squared... (and so on).
Oh yea it's also a graphing calculator thus it can graph functions. It graphs the standard y = 3x + 2 graphs but it can also do z(x,y) = 3y + 2x (ie 3d graphs)... On this one I will issue a little warning... It does more complex graphs OK... not great but OK. It can't graph multiple planes intersecting or anything along those lines and the graphs are wire frame and hard to understand.
The final thing I would like to say (as this is getting rather long) is that Yes this calculator does beat the TI 83. Even though the 83 is the standard in many schools it doesn't do the formatting or have the 30 operation memory. It is also slower and has fewer pixels on it's screen which means that you get sharper easier to read lines on your graphs on the 89, and you get them faster.
Ok the truly last thing I will say. Don't get this calculator if there is any way you see yourself losing it (unless you feel that you have lots of money to burn). It is a $150 machine and I carry mine around school all day long. Personally after having the thing for over a year I've only almost lost it once... But when I did I nearly went insane because I would not be able to replace it for a while and I couldn't think up what I would do in the interim.
Ok that's it... Overall I think if you are serious about doing well mathematically and you want a good tool that will last a long time the TI-89 is the way to go... {Oh yea you can use it on the SAT's}
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