How come Lambda Calculus is a calculus? 
Possible Duplicate:
What do Algebra and Calculus mean? 

Where are the numbers? derivatives? integrals? limits?
If I understand it correctly, lambda calculus is all about symbols. There are no numbers or operators like addition or multiplications except in a very abstract way like Church encoding and alike. The way I see it, it has nothing to do with what we called calculus in high school or university. Insights?

Calculus is here what would be called Kalkül in German or calcul in French, coming from latin calculus "stone (used for computation)" and denotes a formal system of rules. Thus lambda calculus is not the same as calculus in the sense of differential and integral calculus (which e.g. in German is called Differential- und Integralrechnung, not Differential- und Integralkalkül)
