Canon 12-Digit Printing Calc w/Tax, 3-13/16"x8"x2", Gray12-Digit Portable Printing Calculator with tax and business calculations prints 2 lines per second in purple. Time calculation lets you calculate time-based fee structures, while profit margin calculation can be calculated with the touch of a few keys. Tax rates can be stored and recalled whenever needed. Functions include tax calculations, sign change, percentage add-on/discount, cost/sell/margin, round off/down and decimal point functions at the touch of one of two keys. Calculator runs on AC power with an optional adapter (sold separately) or battery power with four AA batteries (sold separately) and shuts off automatically after seven minutes of nonuse. Calculator also features a battery strength indicator.