I know it's a bit late, but because I'm Australian it's the first I've seen it =P From the recodings i've taken in my solo dungeoneering the actual bonus rooms increase for all rooms unlocked is closer to +12.6%. So 100*1.126 = 112.6, which rounds to 13. And 112.6*0.9 = 101.34 and hence your 101%. To be honest I wish jagex would just give out the forumla for these things and stuff like how base XP is calculated, in other news, oh the joys of F2P... http://i46.tinypic.com/167nxia.jpg i thinck he ment the fact that the average exp he gets is 0, not the fact that 113-10= 101 :P