1. Type 1/3 (that's 1, then a slash, and then 3).
2. Select the 1 and press Ctrl + Shift + + (plus sign).
3. Select the 3 and press Ctrl + = (equal sign).
For commonly used fractions, to turn them into AutoCorrect entries, like so:
1. Select the entire fraction you create using the steps above.
2. Choose Tools >> AutoCorrect.
3. Under Replace Text As You Type, select Formatted Text; then type your fraction in the Replace box.
4. Click OK.
Now, the next time you want to create the fraction, just type the fraction followed by a space. Word replaces the fraction with the formatted fraction.
You can save the page in HTML format and cut and paste the fraction into web pages.