ready reckoner

plural ready reckoners · alternative ready-reckoner

1. historicalA printed book or table containing precalculated values, often multiples of given amounts.

   Captain Brazenhead, a sword to the good, listened and learned. To the ready reckoner he was, the accounts were soon cast up.

   1908, Maurice Hewlett, chapter 1, in Brazenhead in Milan

   2 more examples

   Nor did he trouble his borrowers with abstract calculations of figures, or references to ready-reckoners; his simple rule of interest being all comprised in the one golden sentence, ‘two-pence for every half-penny,’ which greatly simplified the accounts[…]

   1838 March – 1839 October, Charles Dickens, chapter 1, in The Life and Adventures of Nicholas Nickleby, London: Chapman and Hall, […], published 1839, →OCLC

   Instead of allowing the peasants to manage their own affairs, and, if they happen to believe that five and four make eleven, to unlearn the prejudice by their own experience in calculation, so that they may gradually understand processes, and not merely see results, bureaucracy comes with its “Ready Reckoner” and works all the peasant's sums for him—the surest way of maintaining him in his stupidity, however it may shake his prejudice.

   1883, George Eliot, “Natural History of German Life”, in Nathan Sheppard, editor, The Essays of George Eliot

2. A computer program which calculates values; an online calculator.