39 Calculati:
a (2000 - 1001). (2000 - 100. 2) .... . (2000 - 100. 20);
b (2010 - 2011).(2010 - 2012) .... (2010-201 . 10).​


Răspuns :

a)999×998×...×980=980×...×998×999= (999×1000):2-(1+2+3+...+979)

=499 500-(979×980):2=499 500-475 300=24 200

b)-1×-2×...