[reactor4]

Thank you, Is there an answer key to those?

[m31415]

Not that I know of, but many of the problems have been discussed online, e.g, calculating the average of the 100th power of sin in under 5 minutes [1], which according to Arnold, if you cannot solve, you don't understand mathematics.

[1]: https://math.stackexchange.com/questions/24533/find-the-aver...