<p>mention private scholarships that you won on other private scholarship applications?</p>
<p>You should mention them only if you are applying for a scholarship that is "need-based." If you've gotten any other scholarships, you no longer "need" that amount. Otherwise, no, there's not a reason to mention them.</p>
<p>Depends. Certain scholarships also have weighty prestige status like the Siemans. That could help your cause.</p>