What kind of battery do I need for an HP42c?
I bought the same number that I found in it (LR43) and the new version was too small. (though it seems to operate when the batteries make contact with th terminals)
If you can help, thanks.



the right size is LR44 ;-)



In alkaline use LR44 but for long life using the Silver Oxide 357 is best. Silver Oxide batteries are a little more expensive than alkaline, about $9 for 3, but depending on use the Silver Oxide can last a couple of years to the alkaline couple of months.

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