In English, it's better style to spell numbers out.
How can I make Word flag this as a grammar error or auto-correct it? (specifically 2007)
Add entries into the Auto Correct to replace "1" with "one", etc.
To set these options, click on the Windows Office icon in the top left corner, and click "Word Options" on the bottom of the window.
Then, click the "Proofing" tab, and select the "AutoCorrect Options" button.
Last, make sure the "Replace text as you type" (Green arrow) is checked. Put what you want to replace in the box that says "Replace" (Blue arrow) and what you wish to replace with in the "With" box (Orange arrow). Click the "Add" button (Dark Blue arrow).
Put in an entry for every numerical value you wish to replace and the corresponding word, and give it a test!