HashCheck is the quickest and easiest way to verify downloaded files on Windows.
Originally developed at code.kliu.org, HashCheck was left to languish for since 2009 until @gurnec took over stewardship of this rather excellent piece of software. They’ve updated it to support newer hashing standards such as
Once installed you can double click on .md5 .sha256 files (and loads more) to verify files.
You can also simply generate checksum files for any files by right clicking on a file and selecting “Create Checksum File…”