The following past papers are very good revision tools and should be used towards the end of the course:

Official SQA Standard Grade Credit (vast majority of questions are very good. No vectors though)

 

Official SQA National 5 Past Papers

 

Unofficial National 5 practise papers (but still good). Courtesy of www.maths180.com:

 

Topic by topic practise:

Nat 5 topic by topic