Any computing application that requires large amounts of numerical calculation(noun)
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Use "number-crunching" in a sentence
"That's about $180 billion in taxes from millionaires, according to number-crunching from the National Taxpayers Union."
"The site that brought baseball's sabermetrics-style empirical number-crunching to football regularly combs the data for new and revolutionary statistics. footballoutsiders.com"
"The data used to produce your figure IV makes it look as if you've done more or less all the number-crunching you need in order to do the nonparametric test so I don't understand why you don't just bite the bullet and do it."