Project Manager's work is to ensure that the teams under him are meeting the deadlines and/or complying with standards and requirements. He also overlooks allocation of resources and personnel if the project requires or to remove personnel due to under-performance, etc. It is not a very technical job.
Right in some cases, Project Managers and Delivery Managers are different if required. Say if 5 Team is working on same project from different location, each location have Delivery Manager tagged with it. Project Managers talk to these DM's only.
Anyway we are going offtopic. The thing is any M level person, is not at all need to be technical. If he has technical background, it's good, otherwise it doesn't matter eitherway.
And to become a developer, Maths is not at all required, if you are not going into Algorithm / Protocol / Game / OS development.
Generally people asks for Maths for Analytical skill / Problem solving skill etc. But if someone have those skills, then maths doesn't matter. He never have to solve maths except in some cases / domains.