RECKONER
reckoner, ready reckoner
(noun) a handbook of tables used to facilitate computation
calculator, reckoner, figurer, estimator, computer
(noun) an expert at calculation (or at operating calculating machines)
Source: WordNet® 3.1
Etymology
Noun
reckoner (plural reckoners)
One who reckons.
(archaic) An accountant; one who computes or calculates.
A computer (technology).
Source: Wiktionary
Reck"on*er, n.
Definition: One who reckons or computes; also, a book of calculation,
tables, etc., to assist in reckoning.
Reckoners without their host must reckon twice. Camden.
Source: Webster’s Unabridged Dictionary 1913 Edition