I need an equation

[Zysoclaplem]

100 sheets of paper.
On each sheet there is 1 dot more than the previous, up to 100 sheets.
So, on the first page, 1 dot.
Second page, 2 dots.
Third page, 3 dots.
And on and on until there are 100 dots on the 100th page.
I need to know the equation to find out how many dots there are in all.

There are 5050 dots, but I know there is an equation, I just cannot remember it.

 

[Vegitto]

E(n+1)n or something like that?

*E = capital sigma.

 

[Syringer]

5049 + 1.

Or, 1 + 2 + ... + n = n(n+1)/2

So 100*101 / 2 = 5050

Or...if you were in elementary school and wanted to solve this, you can just see that you can pair the first and last numbers, i.e. 1 with 100, 2 with 99, 3 with 98, etc..notice that they equal to 101 and that there are 50 pairs..so 50*101 = 5050

 

[TuxDave]

Originally posted by: Syringer
5049 + 1

BZZZZZZZ... wrong. It's 5051-1.

 

[marulee]

Originally posted by: Vegitto
E(n+1)n or something like that?

*E = capital sigma.

Sound fine, and 100 on top of E!

 

[Syringer]

Originally posted by: marulee

Originally posted by: Vegitto
E(n+1)n or something like that?

*E = capital sigma.

Sound fine, and 100 on top of E!

It would be sigma from n = 1 to 100 of just "n".

 

[Zysoclaplem]

Thanks!