calcualte monster damage on me?

I've noticed some strange changes at the levels multiples of 10's, which is when you're supposed to get new equipment. say squids did 60 damage to me during my 7x, but when I turned 80 while wearing the same gear, they started doing say 68. I think there's a Math.floor(level/10) somewhere in the formula. I'd like to think there's a cap level that corresponds to the equipment we have, because I've been wearing the same stuff since level 110 and I don't get hit much more than back then; however this behavior was not very apparent after I got my zhelm ....