# Painfully simple org spreadsheet question

I am an English teacher who is profoundly not good at math, but I want to make some simple calculations with an `org-mode table`. I've tried reading online, but am afraid the explanations are just not simple enough.

With the following table, what formula would I put in the final boxes to calculate the average grade for "draft" and the average grade for "final"? (That is, to calculate the mean of column 2 and the mean of column 3.)

``````| item    | draft | final|
|---------+-------+------|
| plot    |   2   |   3  |
| grammar |   3   |   4  |
|---------+-------+------|
| grade   |   ?   |   ?  |
``````

Will the table recalculate with `C-c *` if I change one of the grades?

Thank you, steven arntson

You need 2 things here:

• The `vmean` function (stands for vector mean)
• The references `@I` and `@II` which stand for the first and second horizontal lines in the table.

So, with the cursor on the draft average cell, type `:=vmean(@I..@II)` and then `RET`. This will add the formula tag at the bottom of the table and the result in the table. Repeat for the other column.

``````| item    | draft | final |
|---------+-------+-------|
| plot    | 2     | 3     |
| grammar | 3     | 4     |
|---------+-------+-------|
| grade   | 2.5   | 3.5   |
#+TBLFM: @4\$2=vmean(@I..@II)::@4\$3=vmean(@I..@II)
``````

If you are going to have many columns, you can also have only 1 formula for all columns thus:

``````#+TBLFM: @4\$2..@4\$>=vmean(@I..@II)
``````

This means that all cells in row 4, from column 2 to the last column (denoted by `\$>`) will have the same formula. By not including column references in the `vmean()` expressions, it automatically refers to the same column.

If you want to round your averages to, say, 2 decimal digits, you may add a format modifier:

``````#+TBLFM: @4\$2..@4\$>=vmean(@I..@II);%.2f
``````

In this case, the modifier says to display floating point (fractional) numbers, with 2 digits after the decimal point.

Documentation for references.

• Thank you so much for taking the time to explain this. At the moment I only understand the beginning of your answer, but it works! I will come back and read through again later, and try to get my mind around the rest. Dec 4 '15 at 1:26