well, for any stat change,for example your speed, when you say +1, it means half your original speed is added on your original speed. Meaning, 189/2=94.5, which you add so 189+94.5=283.5, if you are +1. So for +3 you'll multiply 94.5*3(283.5) and add it to your original speed(189+283.5=472.5). Got it?