Took a look at the current exp file. They have changed the format somewhat to accommodate lvls 115 +11->115 +50 but I still manage to grok it..
Experience required to get to 100 -> 18,579,979,283
Experience required to get to 110 -> 88,343,310,421
Experience required to get to 115 -> 160,093,116,077 (115 +0)
Experience required to get to 125 -> 406,995,603,492 (115 +10)
Experience required to get to 165 -> 3,815,175,525,450 (115 +50) (that's over 3 TRILLION XP folks)
Without counting scrolls, the most exp you can get from a mob in this game is at 115 +50. That value is 86,849 per mob.
When you at lvl 115 +10 you can get a max of 32,689 per mob.
The experience rate is calculated by how many mobs youj need to kill to go up to the next level so looking at lvl 115 +10 ...
to reach lvl 115 +11 you need to get 447548751099 (lvl 126 exp) - 406995603492 (lvl 125 exp) = 4,055,315,000 xp.
To get that 4 BILLION exp, you have to kill AT LEAST 124,057 mobs that are +10 over your level. If you get your hands on some 400x srolls, you can reduce that to 31, 014 mobs to level up.
You are gonna be really busy - get your HK's warmed up folks!