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A keypad is a set of buttons arranged in a block or "pad" which usually bear digits, symbols and usually a complete set of alphabetical letters. If it mostly contains numbers then it can also be called a numeric keypad. Keypads are found on many alphanumeric keyboards and on other devices such as calculators, push-button telephones, combination locks, and digital door locks, which require mainly numeric input.
Uses and functions 
A computer keyboard usually has a small numeric keypad on the side, in addition to the other number keys on the top, but with a calculator-style arrangement of buttons that allow more efficient entry of numerical data. This number pad (commonly abbreviated to "numpad") is usually positioned on the right side of the keyboard because most people are right-handed.
Many laptop computers have special function keys which turn part of the alphabetical keyboard into a numerical keypad as there is insufficient space to allow a separate keypad to be built into the laptop's chassis. Separate external plug-in keypads can be purchased.
As a general rule, the keys on calculator-style keypads are arranged such that 123 is on the bottom row. Whereas, in a telephone keypad, either in a home or mobile phone, there will be the 123-keys at the top. A phone key-pad also has the special buttons labelled * (star) and # (octothorpe, number sign, "pound", "hex" or "hash") on either side of the zero key. Most of the keys on a telephone also bear letters which have had several auxiliary uses, such as remembering area codes or whole telephone numbers.
The reason that the keypad of keyboards and calculators are different is that the first security keycodes had been invented before the touchtone telephone, and did not require the extra + - % / keys and so the touch tone adopted this 1, 2, 3 at the top rather than 1, 2, 3 at the bottom as it too only required 12 keys.
Keypads are also a feature of some combination locks. This type of lock is often used on doors, such as that found at the main entrance to some offices.
See also 
- Keyboard (computing)
- Telephone keypad
- Push-button telephone
- Silicone rubber keypad
- Numeric keypad
- Keyboard technology
- Mobile phone
- Digital door lock
- "Monmouth man, inventor of touch-tone keypad, dies at 94". The Star-Ledger. February 9, 2013. Retrieved 2013-02-09.
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