This is the official website of the Daemon system editor. Here you can find a netbook with the official rules of the system.

https://www.daemon.com.br/home/

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Calculation of Modifiers

rounding
Mathematician - round()
Above - floor()
Below - ceil()

Methods
d20 - Mod=floor((Attribute-10)/2)
Daemon - Mod=round((Attribute-13.5)/2)
Ultimate - Mod=floor((Attribute-10)/3)

Observation
Modifiers or Bonuses are values ​​derived directly from the characters' Attributes and usually affect some rolls such as damage rolls, for example. While several ways to calculate such values ​​exist, some are more commonly used in everyday life.

In the D20 method, a modifier is usually calculated by subtracting 10 from its value and dividing the result by two. If necessary, round down.

In the Daemon method, a table is usually followed, but the calculation was found by Daniel "Nerun" Rodrigues of Gurpzine. In an article, he points out that the bonuses are calculated by subtracting 13.5 from the attribute, dividing the result by two and mathematically rounding the result, that is, to the nearest whole number.

In the Ultimate method, 10 is subtracted from the attribute and divided by three, rounding the result down.

However, it is impossible to cover all possible combinations and since Daemon is a system that supports a wide range of changes and house rules, feel free to design the combinations as desired.