I am a grade 10 student, and we needed a scientific calculator for math class. The school has some of these floating around, and our teacher recommended these over Sharp name brand because this has all of the functions that we basically need, and at the same time, they are very easy to function and see what you are doing because there is a 2 line display, which is nice because sometimes if you make a mistake putting in the numbers, then you will get the wrong answer, so this way, at least you can confirm before writing your answer and then noticing it is all wrong and having to redo it all over again. This calculator has become my new best friend in math class! What happens when the battery dies on the one I bought (although it runs on battery and solar, which is nice)? Well, I would try changing the battery first, and if it still won't work, I would still want to buy the same one because it is so easy to use and you get used to working it, and when I try using another different one (like Sharp,etc), I do not know how to work it. Would I recommend this model to a friend? YES, I ABSOLUTELY WOULD! Thanks Texas Instruments for making such a great calculator!