Texas Instruments Ti 89 Titanium Calculator By orangewalkman on Sep 28, 2007 - Updated Oct 15, 2011

I bought this calculator while pursuing my engineering degree in college and I have to say "It rocks". It has so many functions that I can't even use most of it unless I am a full-time engineer. It performs some calculus calculation both numerically and symbolically which is useful at times. I also found that it is very useful to install new applications or transfer data through the USB connectivity. The cellsheet is a bit sluggish in my opinion. It performs complicated calculation quicker than some of the TIs I have used. However, the battery life is a bit short which only last 3-4 months under non-continuous usage. The size is also a plus since it performs on the same level but is much smaller than the TI-Voyager version. Love it!