number cruncher 
/-ˈkrʌntʃɚ/ noun
plural ∼ -ers /-ˈkrʌntʃɚ/ noun [count] : a person who collects and studies information in the form of numbers
▪ The number crunchers in Washington are expecting a budget surplus by the fall. ▪ the company's number crunchers
▪ The number crunchers in Washington are expecting a budget surplus by the fall. ▪ the company's number crunchers
— number crunching noun [noncount]
▪ doing some number crunching
▪ doing some number crunching
