Translation of "Forthwith" in German

I demand that he leave forthwith.

Ich verlange, dass er unverzüglich geht.

- Mathematicians are like French people: whatever you tell them they translate it into their own language and turn it into something totally different.
- Mathematicians are like some Frenchmen: whatever you say to them they translate into their own language, and forthwith it is something entirely different.

Die Mathematiker sind eine Art Franzosen: redet man zu ihnen, so übersetzen sie es in ihre Sprache, und dann ist es alsobald ganz etwas anders.