The most test is tricky, im not gonna lie, it comes down to being able to do alot of questions with ever more info in a very short amount of time. Don't try to answer all the questions you wont be able to. They want to see how you will be able to handle stress. Maybe practice your mental math, but in short their is nothing you can do to prepare for it, you either have what it takes or you don't, its not a test you can fake your way through.
The interview isn't bad, just be prepared for the stress of having 4 very senior people asking you questions, just be honest and answer to the best of your abilities.
If you have anymore questions PM me and ill be happy to answer them.