On Sun, 04 Feb 2018 11:51:08 -0500, "(PeteCresswell)"
wrote in

- Each reads a different temp from 68 to 74 degrees.

For cheap thermometers, that's not bad. Just take the average of the
four and then calculate the difference between the average and each of
the four and use that as a correction factor for each of the four.
That will probably bring you to a 99.9% accuracy for each of the four.

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