# Can you solve this brainteaser?

Even though I actually know the answer to this one, I still cannot "wrap my brain" around it.

As you may recall my mentioning on occasion, I'm a member of the "How Things Work" yahoo newsgroup. This group involves an on-going discussion that bounces from topic to topic with the agility of a mountain goat. Recently, someone on the group mentioned that something had reminded them of an "old chestnut" problem as follows:

"I have a mighty ball of string, 40 million metres of it, that reaches right round the world.Now, by a Magick I shall not disclose here, I lift the string a metre off the ground (and sea), all the way round.

How much extra string will I need to close the gap?"

Actually, let's take a step back, because the "40 million meters" mentioned above is simply a close approximation to the actual circumference of the Earth. In order to make sure that we're all starting from a level playing field, let's say our piece of string is wrapped around the equator and that that the equatorial diameter of the Earth is 12,760 km (the polar diameter is 40 km less at 12,720 km).

Let's also assume that the surface of the Earth is perfectly smooth (no mountains or anything). So, if we were to magically lift our piece of string 1 meter off the ground, how much extra string would we need to "fill the gap"? Email me your thoughts and I'll post a compendium of answers in a few days time.

Questions? Comments? Feel free to email me – Clive "Max" Maxfield – at max@techbites.com). And, of course, if you haven't already done so, don't forget to Sign Up for our weekly Programmable Logic DesignLine Newsletter.

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