Hi Rosen and Atgxtg! Thank you for your questions!
Have a look to the character sheet (its a draft, we're working on it, but it's 95% the final one):
http://www.shintiara.com/single-post/2017/01/02/Modern-D100-Character-Sheet
the D100 core mechanic involve a single percentage for each character: the Inner Strength. Anything else in the game just give Advantages or Disadvantages to the same roll-as-or-under goal, modifying the real probability of success.
This helps both the players to understand instantly if they had success or not and the Judge (GM) to create a narration-driven game-flow. In fact, in Modern D100 players are free to narrate their actions ("I approach the enemy against the light, in order to cover my movements and attack") and then apply their standard Advantages or Disadvantages (as an example "+2 on Combat", based on mental and phisical aptitudes + specializations.
On top of standard modifier, the Judge could define other Advantages or Disadvantages, evaluating the specific situation as narrated (i.e. "approaching against the light" could give nothing, +1 or more depending on Judge decision). So Players do share some narrative authority with the Judge, describing actions before and after rolling the dice.
How Advantages/Disadvantages apply?
Players roll another d10 die (the Asset Die), together with the percentile d10s (one from 10 to 00 - tens - and one from 1 to 0 -units).
Then they can Add or Subtract as much tens as the result of the Asset Die, up to the Advantages/disadvantages they have.
As an example if I have Inner Strength 50% and 3 Advantages (+3)
GOAL: 50 %
D100 (precentile roll) = 60 (tens) 4 (units) = 64 this should mean a fail.
D10 (asset die) = 40
Now, you can confirm only 3 advantages, so you can subtract a maximum of 30 point to tens, higher results are unuseful.
Result = 64 - 30 = 14
SUCCESS!
I reported the results of the Asset Die expressed in tens ("40" and not "4") because we suggest to use the tens die (form 10 to 00) in order to make faster calculations. The maximum number of advantages or disadvantages is 9. the 00 result in the asset die means zero modifier. an action with +10 advantages is automatic (and the contrary).
Go and take the 3 dice and try to roll all of them a couple of times: it's quite easy.
I hope this could help!