I am still preparing for a number of job-tests. At the core of the application process there is usually a numerical test which needs to be performed at high speed. It mainly concerncs basic math so nothing too fancy. A mathematician is not naturally good at performing high-speed mental math so it is nothing that requires a lot of practice (at least for me).
I came across arithmetic-zetamac to practice your speed at basic arithmetic. On the basic settings you just need to solve as many equations as you can in 120 sec. I started at about 20 points. And now, a few weeks later, I am averaging at about 40. Slowly moving to a score of 50. :o)
Yay above 40:
So a lot of successful applicants seem to have a gotten a score of about 60 so I still have a long way to go...
Here is another website for arithmetic practice. It includes a bit more advanced type of computations but nothing which would not be considered in the category of basic. I will probably give it a serious try once I get a more reasonable score on the arithmetic-zetamac game.