calculation (n.) Look up calculation at Dictionary.com
late 14c., "art, manner, or practice of computing by numbers," also "the process of making a horoscope," from Late Latin calculationem (nominative calculatio), noun of action from past participle stem of calculare "to reckon, compute," from Latin calculus "reckoning, account," originally "pebble used in counting," diminutive of calx (genitive calcis) "limestone" (see chalk (n.)). From early 15c. as "the result of reckoning, the solution for a problem."