I posted this in another area, but it is one of my favorite problems of all time and no one has solved it yet. A few things to note. Solving this like a proof in algebra makes this a lot easier. Also, I won't post an answer for a few days, as I have to type it up and I'm lazy. There is a short answer, but that is the easy cop out.

1) Start with VG
2) If you possess a string whose last letter is G, you can add an C at the end
3) If you have Vx you can add Vxx to your collection
Example: (VGC => VGCGC)
4) if you have GGG you can replace that with C
5) If you have CC you can drop it
6) Find a way to get VC

I'm still working on nordlead's brainteaser but since it's so hard, I'll add an easy one to keep the thread rolling :

Find the next number is the following series :

1
11
21
1211
111221
312211

1
11
21
1211
111221
312211
13112221
1113213211

It's fairly easy (if I'm correct, otherwise it's hard as heck :P)

All numbers are groups of 2. First number tells how many, and second tells you which digit.

It's 1211 because there is one two (thus 12) and one one (thus 11)

The final number (after the last I wrote) is in the area it gets difficult, and is something along

31131211131221

Three times 1 (31) 1 times 3 (13) 1 times 2 (12) 1 times 1 (11) 1 times 3 (13) 1 times 2 (12) 2 times 1 (21)

Correct? I kinda doubt it.

Anyhow,  I add one, but if my answer is incorrect, continue on Truck's.

If you take  Tellus' circuit (about 40000KM) and add 10M to it, how much longer is  Tellus' diameter than before the change?

Edit: Crap, I didn't see Nordleads. Skip mine and take his, it is probably better.

You got it Oyvoyvoyv. It is really simple unless you try to find a mathematical answer which wouldn't work. I should have written them on the same line, it would have been harder to find (1, 11, 21, 1211, 111221, 312211)

Quick question : Is the Tellus circuit a perfect circle?

its easy

flip one switch on and wait a few mintues (lets bulb heat up) then turn it off

move quickly and flip another switch

walk briskly over to teh room and you will now have one lamp on (the switch you flipped just now)

one lamp off with a cool bulb (the switch you never flicked)

and one lamp off but with a warm bulb (the one you flipped first)

In this brainteaser it is, but in reality I doubt it.

Gahh, Nordlead put up a hard one. I've been trying for 1 hour now, but I haven't made it yet.

Really a pickle.

Okay if it's a circle :

It adds 3,183098862 meters to the diameter.

@ nordlead : Your brainteaser is EVIL!

I already gave you a hint. I had to do it with no hint at all.

anyways, I would say the same as truckasoarus for the Tellus circuit question, but I feel as if that is too easy and it is really a trick.

He's correct.

I generally dislike way to hard brainteasers in a row, so I took a relatively easy one.