How do I stop OpenOffice.org from changing my decimals into fractions?

OpenOffice.org is changing my decimals into fractions. How do I reverse this setting?

To reverse this setting:

1. select Tools-AutoCorrect/AutoFormat-[Replace].
2. near the top of the list, find the replacement choice for '.5'
3. select this replacement description and click on the 'Delete' button to the right of the dialog
4. click 'OK' at the bottom of the dialog to apply the change.