You can do that by modifying your styles formatting of the text in question.

Right-click on the style and select Modify to get the "Modify Style" menu; Click on Format (lower left-hand corner) and select Numbering to get the "Numbering and Bullets" menu; Select "Define new number format" to get the "Define new number form"; Under "Number Format" insert a "0" behind the existing "1" so that it reads 10.; Select OK. It should be set to your liking. However, if you are not already aware of the styles and numbering within Word, I strongly suggest you take the time to review the following links and become real familiar for future reference.

Links:
Understanding styles | ShaunaKelly.com
Numbered Headings