Aurora DT830P desktop calculator is ideally suited to all your calculating needs Cost / Sell / Margin calculates ANY variation. Programmable one-touch Tax feature ideal for adding or subtracting VAT Automatically turns on & registers when pressing ANY key, so you can start using the machine instantly Large 12 digit fixed angle LCD display Rounding & Add mode Decimal point selector settings: 4,2,0 & Floating Large plus key for easy entry Patented long answer bar for easy entry Metallic finish +/- Change sign key Backspace correction key 3 key memory Percentage Double zero key Rubber feet (for desktop use) Solar powered with battery backup Auto power off Unit size (WxDxH): 180x133x31mm Backup battery ref: LR1130 or BSR54H included