This reply was originally posted by user dmebrown in ADDitude’s now-retired community.
Timez Attack by http://www.bigbrainz.com/ is a good game.
Also, Mister Numbers by http://www.patternplaymath.com may be a fun way to learn. Look at his YouTube videos for examples.
Finally, the book “Five Times Five is Not Ten” workbook by http://www.longevitypublishing.com/.
To start on a clean slate, I would purchase the workbook first, then follow it by the Timez Attack game.
Good luck with everything. My daughter is heading into the 9th grade and forgot a lot of her facts, so I we refreshed it with the Timez Attack game. Now we need to focus on fractions (adding, subtracting, multiplying and dividing).