5. The numeral 5 in a blog post title is a secret signal to Google’s SEO filters that the post is a Super-premium-level link and should be moved up in the page rankings.
4. No need to worry about how to organize the post’s contents.
3. 5 is not the same as 10, so David Letterman won’t be able to sue you for stealing his bit.
2. 5 is a perfect blogging number: you can use one hand to count, and still be able to type with the other.
1. The numeral 5 looks very much like the letter S: because the most powerful link-bait word also begins with S, by a process of unconscious transference many readers will click the link hoping to get lucky.