Wiktionary
n. An accountant or other person who deals with the calculation of numbers as a profession.
WordNet
n. someone able to perform complex and lengthy calculations
a computer capable of performing a large number of mathematical operations per second
Usage examples of "number cruncher".
Next to her grandfather's NN core was a Commodore bioware number cruncher, a maroon hexagonal block fifty centimetres across and twelve high.
Cray's dream was to build a number cruncher capable of 150 to 200 million calculations per second.
She suddenly realized that in the last eight years she had worked her way up to be the head soap drone and number cruncher, and where had it gotten her?
He was proud of his bookkeeping, and would certainly have earned more per annum as a number cruncher for any midlevel firm than he did dealing.
Using a throwaway number cruncher instead of hooking in to the mainframe seemed a reasonable way to keep the data away from him, so long as I didn't ever network it with any other system.