% Chance, is this code efficient and correct?

public class Spell {

// chance = (0, 100>
private int chance;

public void execute() {
    if (chance < 100) {
        /*
        chance:80
        random:40 ... if(true) ... succeed

        chance:80
        random:80 ... if (true) ... failed

        chance:80
        random:81 ... if (true) ... failed

        chance:79
        random:80 ... if (false) ... succeed

        chance:66
        random:<0,65> (66 numbers) ... if (false) ... succeed
        random:<66,99> (34 numbers) ... if (true) ... failed


         */
        if (chance <= (int) (Math.random() * 100)) {
            System.err.println("failed");
            return;
        }

    }
    System.out.println("succeed");

}

//Test
public static void main(String[] args) {
    Spell spell = new Spell();
    spell.chance = 80;
    spell.execute();
}

}

Is this correct way to calculate chance? I need certain things to happen chance% of times. I wonder whether I did some mistake here or whether it works.

Let's say we have chance = 80, I need it to succeed in 80% of times and fail in 20% of time. There are souts for that in code, where I will add a function later.