The Jargon File (version 4.4.7, 29 Dec 2003):

number-crunching
 n.

    [common] Computations of a numerical nature, esp. those that make extensive
    use of floating-point numbers. The only thing Fortrash is good for. This
    term is in widespread informal use outside hackerdom and even in mainstream
    slang, but has additional hackish connotations: namely, that the
    computations are mindless and involve massive use of brute force. This is
    not always evil, esp. if it involves ray tracing or fractals or some
    other use that makes pretty pictures, esp. if such pictures can be used
    as screen backgrounds. See also crunch.

    [74-12-25]

    Hydrodynamic number-crunching.