Number-crunching is the work of going through a lot of numbers and calculating results. It is informal, a little playful, and a little tired: people say it when the maths is heavy and not very exciting — spreadsheets, accounts, test scores, machine data. A person who does this all day may be called a number cruncher. You crunch a biscuit with your teeth; here you 'crunch' numbers, as if you are chewing through a pile of them. Offices, science labs, and news reports all use it. It is not a rude word, but it is not for a formal contract either.