Summary: This calculator works great in both lighted areas and with the included battery. The only potential problem is if the battery goes out and needs replacing. Casio voids the warranty if it is opened by anyone but a Casio repair person. It looks to me that one could just open the thing up and put in a new battery, but be aware...I haven't tried to do this yet. If you use this in brightly lit areas, the battery issue is moot.
Summary: Calculator did not work properly. Only worked in direct sunlight and the tax designation kept reverting back to a previous tax rate. I recently returned it; now awaiting refund. If refund is forthcoming, I will be satisfied.
Summary: I needed to replace a solar calculator that was hard to see. The display was small and I had to hold it directly under the light for it to work. This calculator has a large display so I can see it clearly. It runs on solar and battery so I don't have to hold it to use it. It's a nice size to work with and looks smart on my desk. I've been using it for about a month. Happy.
Summary: I got this to replace a Canon brand that I had gotten on Amazon. I had to reset the Canon once in a while, and then it just wouldn't work. So far, this Casio is working well. I like that it's solar-powered and that it has the ability to automatically add your local tax with the press of a button. It's actually only 4" x 5-1/2", NOT 6.2 x 9.1 as described.