a short statement that consumes lots of CPU cycles

I'm seeking a(very) short statement(in any language) that can make the CPU busy for like a second or a half. The statement should consume CPU cycles, not IO stuff开发者_如何学编程.

Psuedocode:

A = 2
StartTime = GetTime()
While (GetTime() - StartTime) < 1.0
  A = A * 2

Using java BigIntegers, you could try and implement http://en.wikipedia.org/wiki/Ackermann_function.

That'll keep you going for a while.