Fun Math Drill Computer Games

I’m looking for fun math drill computer games for a 7-year-old who is pretty good at math. He’s learning two-digit multiplication (12 x 34), two-by-one-digit division yielding fractions (15 / 4), and extremely simple algebra (4x + 13 = 31). The conceptual work and problem-solving skills are being taught. But he needs some time putting the principles into practice, and my sense from knowing his temperament is that a fun computer game — as opposed to paper-and-pencil work, or even pure online drill without fun elements — is most likely to keep him engaged.

Can any of you recommend some such games? Let me know, please, if you can. Many thanks!