Calculați suma. Vă roggggg mult!!!!!!!!

[tex]\frac{1}{1*2}+ \frac{1}{2*3}+ ... + \frac{1}{2019*2020} =[/tex][tex]\frac{1}{1}- \frac{1}{2}+ \frac{1}{2}- \frac{1}{3} ... + \frac{1}{2019}- \frac{1}{2020} =[/tex][tex]\frac{1}{1} - \frac{1}{2020}[/tex][tex]= \frac{2019}{2020}[/tex]