Is there a way to define and sum arithmetic sequences in Numbers?
Here's how I'm trying to apply it.
I have a value in one cell. In the next cell, I'm trying to write a formula to add all integers equal or lower than the value, stopping at 3. So if the value in the first cell is 9, the next cell returns 42 (9+8+7+6+5+4+3).
Can Numbers do this?
Hi jct,
A quick google search landed me here:
http://www.wikihow.com/Sum-the-Integers-from-1-to-N
and gave me this formula to sum all integers from 1 to N:
(N(N + 1))/2
they also have an easy explanation as to how this formula works.
but you don't want to count 1+2 so you will have to subtract that.
Put the formula in your second cell with N being your first cell and you are done!
quinn
There are a couple ways:
1) brute force:
2) elegant (t_quinns suggestion)
1) Brute force:
create a table with the a count in column A and the sum of the count in column B:
B1=SUM($A$1:A1)
this is shorthand for... select cell B1, then type (or copy and paste from here) the formula:
=SUM($A$1:A1)
select cell B1, copy
select column B (click the "B" in the column header)
paste
2) The more elegant way is to use the formula t_quinn provided:
type "the number" in cell D1 and enter the formula in E1.
E1=(D1×(D1+1))÷2
How do you sum an arithmetic series/sequence?
