Question

what is 1+2+3+...........+999999998+999999999+1000000000=

?

Answer 1

sum(1 to n) = (1/2)(n)(n+1)

e.g., sum (1 to 10) = (1/2)(10)(11)= 55

Answer 2

cool what subject did you learn that in?

Answer 3

I discovered it myself in high school. Found later was first done by Gauss centuries ago. Thanks for asking.

Answer 4

nice thanks for that