Reversing data to figure out the math behind generating values using Eureqa Pro

So I needed an easy way to get the formulars back from the data in a game.
For example to know how Damage and Chance to Hit are calculated so that I can emulate this server side.

I needed something simple to use, there was R which I learnt about at work but its unnessecarly complex.

Erueqa Pro has a spreadsheet interface to enter your data, you define var for each column.
dex hitrate
1 5
2 10
3 15
4 20
5 25
6 30
7 35
8 41
9 46
10 51
11 56
12 61
13 66
14 71
15 77
16 82
17 87
18 92
19 97
20 102

I then went to the Set Target area. I knew Floor, Ceil or Round must be used as the value is always a whole number but the total goes up in a pattern like 3 2 2 2 3 2 2 3 2 2 2 which tells me theres flooring or something going on.
http://www.nutonian.com/download/eureqa-desktop-download/