Using the numeric keypad
The numeric keypad arranges the numerals 0 to 9, the arithmetic operators + (addition), - (subtraction), * (multiplication), and / (division), and the decimal point as they would appear on a calculator or adding machine. These characters are duplicated elsewhere on the keyboard, of course, but the keypad arrangement allows you to rapidly enter numerical data or mathematical operations with one hand.
Numeric keypad
To use the numeric keypad to enter numbers, press Num Lock. Most keyboards have a light that indicates whether Num Lock is on or off. When Num Lock is off, the numeric keypad functions as a second set of navigation keys (these functions are printed on the keys next to the numerals or symbols). You can use your numeric keypad to perform simple calculations with Calculator.
Three odd keys
So far, we've discussed almost every key you're likely to use. But for the truly inquisitive, let's explore the three most mysterious keys on the keyboard: PrtScn, Scroll Lock, and Pause/Break.
PrtScn (or Print Screen)
A long time ago, this key actually did what it says—it sent the current screen of text to your printer. Nowadays, pressing PrtScn captures an image of your entire screen (a "screen shot") and copies it to the Clipboard in the computer's memory. From there you can paste it (Ctrl+V) into Microsoft Paint or another image editing program and, if you want you can print it from that program.
More obscure is SYS RQ, which shares the key with PrtScn on some keyboards. Historically, SYS RQ was designed to be a "system request," but this command is not enabled in Windows.
Tip : Press Alt+PrtScn to capture an image of just the active window, instead of the entire screen.
ScrLk (or Scroll Lock)
In most programs, pressing Scroll Lock has no effect. In few programs, pressing Scroll Lock changes the behavior of the arrow keys and the Page Up and Page Down keys; pressing these keys causes the document to scroll without changing the position of the cursor or selection. Your keyboard might have a light indicating whether Scroll Lock is on.
Pause/Break
This key is rarely used. In some older programs, pressing this key pause’s the program or, in combination with Ctrl, stops it from running like what Alt+F4 do now.
Other keys
Some modern keyboards also called as Multimedia keyboards come with "hot keys" or buttons that give you quick, one-press access to programs, files, or commands like calculator. Many models have volume controls, scroll wheels, zoom wheels, and other gadgets. For details about these features, check the information that came with your keyboard or computer, or go to the manufacturer's website.
