Although many people use as calculator their smartphone (in some cases even with HP calculators), it is true that for chain calculations there si nothing like a hand-held calculator with a good key feedback. The same way, we can find Blackberry fanatics that swear by their keyboard.
Due to the limit to what a calculator can do, even 40 year old calculators have enough features to be 100% useful nowadays. And you may have one or several in your back yard. It is likely that it doesn't work when you put fresh batteries and try to switch it on. Do not worry: unlike modern electronics, most of these calculators are very easy to repair, and in most cases by yourself. More often than not, you will NOT be required to solder (only in the rare case the screen is damaged) - just some clever mechanics will be enough.
Also it is a way of contributing to our environment by reusing what should last forever.
You can find on our pages several methods to repair the most frequent of these calculators - look no further than "the HP41 corner":