The numpad's keys are digits 0 to 9, + (addition), - (subtraction), * (multiplication) and / (division) symbols, . (decimal point), Num Lock, and ↵ Enter keys.[4] Laptop keyboards often do not have a numpad, but may provide numpad input by holding a modifier key (typically labelled Fn) and operating keys on the standard keyboard. Particularly large laptops (typically those with a 15.6 inch screen or larger) may have space for a real numpad, and many companies sell separate numpads which connect to the host laptop by a USB connection (many of these also add an additional spacebar off to the side of the zero where the thumb is located, as well as an additional 00 key typical of modern adding machines and cash registers).