ready reckoner(redirected from ready reckoners)
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(Mathematics) a table of numbers used to facilitate simple calculations, esp one for applying rates of discount, interest, charging, etc, to different sums
A small book of assorted tables that was mainly used by store owners who did not want to take the time to do the necessary arithmetic, or by those who did not know how to do the calculations. Included were tables such as interest amount vs. time and rate, board dimensions vs. board feet, and cistern capacity vs. cistern dimensions.