According to your sig you are 4,197,337 exp from 99 defence. That will require you to inflict 1,049,335 damage to achieve your goal. (4,197,337/exp per damage dealt[4]) 1,049,335/4= slayer exp (every 4 damage dealt, you recieve 1 slayer exp) You will recieve (APPROXIMATELY) 262,333.5625 slayer exp on your quest to 99 defence. Add 262,333 to your current slayer exp and see what level that is.