Hewlett-Packard calculators have a serial number which can be used to find the date and country of manufacture. It is known that in practice the HP factories often left the week part unchanged for a while so you cannot rely on the week number part of the serial, it should be considered as a rough guide only. As later serial number formats repeat you may get more than one date returned. If this is the case you can look up the specific model's date range to find out which years are valid.
HP calculator serial number :
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