The initial rating

Here is how the system establish the initial rating of a new player:
1) Find the average grade of your section. Ex: if you have 2 players in your section, one in grade 4 and one in grade 6, the average grade of your section will be 5. So here, 5,5 would be 5 not 6 (5,9 would also be 5).
2) Find the average performance of your new player. If he did 2.5 out of 5 games: 2.5/5 * 100 = 50%

Here are some values you will need:
Note the new table is official after September1, 2007
Kindergartena0=100 aa0=250
Grade 1a1=110 aa1=300
Grade 2a2=130 aa2=350
Grade 3a3=150 aa3=400
Grade 4a4=180 aa4=450
Grade 5a5=220 aa5=500
Grade 6a6=250 aa6=550
Grade 7a7=290 aa7=600
Grade 8a8=330 aa8=650
Grade 9a9=370 aa9=700
Grade 10a10=420 aa10=750
Grade 11a11=420 aa11=750
Grade 12a12=420 aa12=750

Here is the formula:
aa + (performance*a / 100) = Initial rating

So it would be:
aa for grade 5: 500 + (performance: 50 * a for grade 5: 220 / 100)

Finaly:
500+(50*220/100) = 610

Once everybody has a rating, here is the formula: How to calculate the rating