This may have been stated before, but I could not find it with search. But here are some interesting calculations I did on anime/mania to correct another post's math.

Given one episode and one anime per week, the anime will be covering the same topic as the manga sometime around the following time:

Anime Ties Manga
Date: Around Two years time. May-July 2006
Episode: Somewhere in the 180s-190s
Chapter: Somewhere between chapter 311 and 330

Now I have heard that the anime is supposed to run for 250 episodes. If this is true then one of three things has to happen:
a. Chapters will begin to be released more than 1 a week
b. Episodes will begin to be released slower than one per week (think reruns).
c. The quality of the episodes will drop.

Which of these three options do you guys think is the most likely?

Reasoning Explained: Ignore this if you hate math
Notes and Assumptions before we begin
1. The manga began sometime in 1999 according to Naruto Fan. Because of this it has been being put out slower than one per week, but one per week as an estimate is close enough.
2. The anime started fourth quarter 2002 and I forget where I heard this, but it has been coming out close to one per week.
3. I read in the naruto mania forum that anime and and manga only have 51 episodes per year because of something called golden week. I am ignoring this because I don't think one week really matters, so all my equations are off by a couple weeks.
4. Obviously previous release rate of the anime / manga have no direct correlation with future release, but it can be used as a good estimate.
5. This calculation is based off episode 85 which roughly corresponds to chapter 148 (just part of it)

A. Episodes per chapter
Episode 17 roughly corresponds to chapter 28 = 1.64 chapters per episode (28 chapter / 17 episode)
Episode 39 rougly corresponds to chapter 68 = 1.74 chapters per episode
Episode 64 roughly corresponds to chapter 107 = 1.67 chapters per episode
Episode 85 roughly corresponds to chapter 148 = 1.74 chapters per episode

Note that throughout the life of the anime, each episode has covered around 1.7 chapters. This will be the number we use.

B. Equations
We want to find the number of weeks before the chapter and the episodes tie. Given 1 episode and one chapter per week and that we are at episode 85 and chapter 217 we have the following equations.

Equation I: tied_episode = weeks_left (episode/week) + 85 episodes
Equation II: tied_chapter = weeks_left (chapter/week) + 217 chapters

Given that there are 1.7 chapters per episodes we have
Equation III: tied_episode * 1.7 (chapters/episode) = tied_chapter

C. Algebra
Given Equation I and III we can modify I so that:
Equation Ib: 1.7(chapter/episode) ((tied_episode) = (weeks_left) (episode/week)+(85 episodes))
Multiplying out we get
Equation Ic: tied_chapter = 1.7 weeks_left (chapters/week)+ 145 chapters

Therefore, we can set equation II and Ic equal to each other
Equation IV: 1.7 weeks_left (chapters / week) + 145 chapters = weeks_left(chapter / week) + 217 chapters

Solving, we have:
Equation IVb: .7 weeks_left (chapter / week) = 72 chapters
therefore
weeks_left = 103 weeks = roughly 2 years = summer 2006
Chapter = 217 + 103 = 320
Episode = 85 + 103 weeks = 188

Other Interesting notes:
At the current rate of production, when will the episode cover the same stuff from the current chapter(217)?
Around April of 2005
What episode will that be?
About 130
What Chapter will be out then?
Around 260

Note: Shuriell of the naruto mania forums had a similar post. He comes up with the 1.7 chapters / week equation and has the basics of equations I and II, but the post does not correctly handle terms and I believe the calculations in that post to be incorrect. But he did have some good equation layouts that I followed in my post. To see that thread go here.

Edit: Fixed a point of grammer.