If you need to download Mathcad 15, for new users. However, here are the legitimate ways to obtain it.
A: Strongly discouraged. These files are often unlicensed, outdated, or modified with malware. PTC does not authorize distribution outside its own servers. ptc mathcad 15 download
If you don't have a license, consider moving to – it supports .xmcd files and is actively maintained. If you need to download Mathcad 15, for new users