Question

Calcule a soma dos múltiplos de 5 compreendidos entre 99 e 999

Answer 1

999-99=900
900/5=180 divisores
an=a1(n-1)r
an=100(180-1).5
an=100+900-5
an=1000-5
an=995

SN=(an+a1).n/2

SN= (995+100).180/2
SN= 1095.90
SN= 98550