Can I sum these numbers with a formula ?
1
2
3
4
5
6
No, Im not looking for ="Sum(Cell___1:Cell_6)".
With "Product" you multiply - I just want to add them.
Like "=1+2+3+4+5+6", but just with a formula. Eg "formulaName(6)".
views:
134answers:
4
+12
A:
You mean:
Sum = n * (n+1) / 2, where n is the last number in the sequence?
BobbyShaftoe
2009-05-04 14:01:59
For the historically interested: Finding this formula is attributed to the German mathematician Karl Friedrich Gauss (1777-1885). In his elementary school the teacher tasked the class to to sum up all numbers from 1 to 100 (hoping he could take a nap in the meantime), Gauss came up with this formula and the correct answer after a couple of seconds.
Tomalak
2009-05-04 14:11:21
@Tomalak, yeah Elementary Proofs professor told me that story too. :)
BobbyShaftoe
2009-05-04 14:14:03
Cant believe I had forgotten all about it. Thanks
Kim
2009-05-04 14:48:18
Which is the same as (n^2+n)/2...I've used this ever since high school, didn't know someone else came up with it. I figured it out for a piece of math coursework. It never crossed my mind to factor it out.
BenAlabaster
2009-05-04 21:18:29
+1
A:
Well... =6*(6+1)/2 ought to do it
For a more general approach, you could put 6 into, say, A1, and use
=A1*(A1+1)/2
Carl Manaster
2009-05-04 14:08:06
A:
Function GaussForm(ByVal x As Integer) As Integer
GaussForm = (x * (x + 1) / 2)
End Function
NickSentowski
2009-05-04 15:45:54
A:
Not very Gaussian, but here's another way:
=SUM(ROW(A1:A6))It's an array formula, so enter with Control+Shift+Enter
Dick Kusleika
2009-05-04 21:15:51