If your laptop has a full keyboard, numbers can be entered from the side of the keyboard turn on by pressing the Num Lock key in the upper right corner. Will light one of the LEDs, if present. Disabled similarly. This is a very convenient feature if you often need to enter numbers from the keyboard to use the calculator and so on. Also it can be used to control various computer games, but lately it is increasingly rare, especially in netbooks.
If you have an incomplete keyboard, find out whether your model of laptop (netbook) panel numbers Num Pad. To do this, follow the corresponding request in the searcher. Also quite simply to find the numbers in the right side letter keys. To enable Num Pad you will need a combination Fn+NumLk. On the screen you should see the icon that informs the user about the change of number mode. Also command to toggle the digits can be any other combination of keys, to read the manual to your device.
If you want to change the button command switching the numbers on those that would be more convenient for you, use a special utility KeyTweak or any convenient program. They are all quite simple to use and have intuitive interface.
If your laptop is missing the Num Pad panel, buy it separately in a special computer store. Mostly they are easy to use, connects to USB port of laptop and included like the built-in keyboard or by pressing a special button, and many of them do not require installation of device drivers. You can also find and wireless versions of the Num Pad.