????????????????? "natural numbers" ???????????
me ges yu meen INTEGER
me thank yu want 5+10+15+20+...965
sum=93,605
this be arithmatik sequens: start=5, step size=3, n=193, last=965
averaej=(start+end)/2=(965+5)/2=970/2=485
sum=n*averaej=193*485
###### if start with 13, step size=13...get n=74, averaej=487.5, sum=36,075