Auto-sizing a pdf inside of a static page

I have some newspaper articles that I wrote and am posting on some static pages on my blog. The articles were scanned into a pdf format, and are displayed that way.

The pdfs though, when the pages are opened come up at 50%, meaning that anyone that wants to read them needs to manually resize. Is there a way to have them come up at 100%, 125%, etc., so they are more easily read without the reader having to manually do it?

I have tried several Google searches trying to resolve this, to no avail. Any help would be truly appreciated.

Thanks,

Martin