You should provide a mechanism other than pagination to reach all the questions and answers on your site. Pagination is a poor navigation technique because:
- It is rarely used by visitors. Usually only 2% of visitors actually use pagination.
- Using AJAX for it makes it uncrawlable
- Even without AJAX, it causes PageRank to dissipate so quickly that by page 4, none of the questions get any juice.
Instead you should:
- Create a sitemap XML file that lists all your content and submit it in Google webmaster toolsWebmaster Tools.
- Use tags to group you questions by theme. Have tag pages that list questions in each tag.
- Link questions directly to other questions using "related" links or something similar.
- Consider expanding the number of items on the first page of pagination. If you have 100 items per page, that means that search engines will be able to find 10 times the amount of content from the first page alone.