Samuel said.... Legendary Items are impossible

But in actuality, 1/10,000 = .0001
But here's where I am getting fuzzy.
So if I drop points into Magic Finder, how greatly does this actually affect the drop rate?
.0002 = 1/5000
.0003 = 3/10000
.0004 = 1/2500
.0005 = 1/2000
.0006 = 3/5000
.0007 = 7/10000
.0008 = 1/1250
.0009 = 9/10000
and .001 = 1/1000
Now that would imply that by only adding 2 points to MF (so that I have .0002) I have effectively cut my search time in half?????
But if I add another 2 (so that I have .0003), I have only cut my search time by a factor of 60%......meaning I haven't really shaved much extra time (a mere 10%) off my search, correct?
2 more (so that I have .0004) cuts time down by 75%? (I've gained a factor of 15% by these two points.)
Am I getting this math correct here? Does the MF really affect the time you have to look for one of these things by that great a factor? (a whopping 50% for merely 2 points added.....) Or is my math completely wrong somewhere?
Help me out please, cause this one has been driving me nuts for 2 weeks now.