reckoner

/ˈrɛkənər/
noun
  1. A person who calculates or estimates something, especially in a business or financial context.
    • The village reckoner kept track of everyone's debts.
    • The old reckoner could add up numbers faster than a machine.
    • She worked as a reckoner for the accounting firm.
  2. A book or table used for making calculations, such as a ready reckoner.
    • The carpenter kept a reckoner of measurements in his workshop.
    • Before calculators, people relied on printed reckoners for math.
    • He used a ready reckoner to figure out the interest on the loan.
What does "reckoner" mean? | whatsthatwordmean | whatsthatwordmean