Código :
for (n=1; n<5; n++) {
//color
color = new Color("firework");
color.setRGB(Math.random()*0xFFFFFF);
//duplicar
duplicateMovieClip("firework", "fire"+n, n);
firen = this["fire"+n];
//principal
firework._x = Math.random()*550;
firework._y = Math.random()*400;
//duplicados
firen._x = Math.random()*550;
firen._y = Math.random()*400;
firen._xscale = firen._yscale=Math.random()*60+40;
firen._alpha = Math.random()*50+50;
} 