I see the reason for your confusion. Let's explain, shall we? See, you get experience for each point of damage you do with a spell, not per cast. So, for example.. One cast you do 20 damage, and we'll say that spell's experience per cast is 3. 20 * 3 = 60 experience. Well, next hit let's say you do 10 damage. 10 * 3 = 30 experience. See what I mean? You get experience per point of damage, not per cast. And when you see how much experience you'll get from a certain attack spell, that's only if you it's max (In parenthesis next to the name). Each normal spell has a max hit, and the magic calculator bases experience off of that max hit. Buut, Slayer Dart has no max hit. It's all dependent on your magic level. So, at 50 magic, the max may be 15. But at 99 Magic, the max may be 30+. And since you're getting experience per damage, and the calculator bases off of max hit, you can't really include that. Get what I'm saying? Sorry if that was just a bunch of mumbo-jumbo. If you don't get it, I'll explain it in another way.