A person who excels at or specializes in calculations; someone skilled in computing or mathematical problem-solving.
From calculus plus the agent suffix -ist, which means 'one who does or specializes in.' Similar formations include 'pianist' (one who plays piano) and 'specialist' (one who specializes).
A calculist is someone for whom numbers are like a language—before computers, institutions like insurance companies and governments employed armies of calculists who could do complex math faster and more accurately than most people.
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