Here is a simple piece of software I wrote to help my children practice basic arithmetic facts. Of course there are no doubt already a thousand or more similar programs out there; but in a few minutes of searching I didn’t find one that did quite what I wanted. I ended up tinkering with this for several hours, and even wrote documentation and made an installer. Free download and screenshot below.
MathDrillSetup.exe (free)
I’ve also published the source code over on Github: http://github.com/kylecordes/mathdrill/tree/master
This software is written in Delphi, and though there is some chance that I am the only developer anywhere using both Delphi and git, hopefully this will be wrong, and someone will fork and offer their improvements.