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Circle of Children

Math brain teasers require computations to solve.


Puzzle ID:#23713
Fun:*** (2.82)
Difficulty:** (1.27)
Submitted By:sk8ergrlAus*****
Corrected By:shenqiang




A number of children are standing in a circle. They are evenly spaced and the 7th child is directly opposite the 18th child. How many children are there altogether?

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How many children are in half of the circle?

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Jun 15, 2005

As usual I got this math teaser the long way. I've got to bone up on my algebra!
Jun 15, 2005

Algebra ain't anything to do with it. Just figure 10 kids either side of them (10) Double it as there are two sides (20), then add the two kids themselves (22)

Bit EZ but i enjoyed it. Thanks.
Jun 15, 2005

riddle is right. There is nothing to do with Algebra. I'm glad everyone seems to like it
Jun 15, 2005

We do these as bonus questions in school all the time!
Jun 15, 2005

my brain hurts
i got 20 but i'm not entirely sure how
Jun 16, 2005

I needed the hint.
but ast least then I got it!

good one!
Jun 17, 2005

good 1 even tho i dont understand y u need to subtract 7 from 18 to get 11 to multiplay it by two?
Jun 17, 2005

Simple, but good.
Jun 22, 2005

Good teaser!
Jun 23, 2005

good 1
Mar 20, 2006

Aug 06, 2006

Sep 11, 2010

I'm such an idiot. I figured out there were 10 kids on the right, and then figured out there were 6 kids before the 7th kid on the left, and hence 4 kids after the 18th kid to the left, for a total of 18 + 4 = 22 kids.

Then I realized I could have just doubled 10 and added 2.

Sigh I'm ashamed of my stupidity.
Sep 27, 2012

The solution assumes that the children are arranged consecutively around the circle.
Jun 03, 2013

The question may be considered by solving a simpler problem. If 4 kids stand in a circle, 1 is opposite 3 and 2 is opposite 4. The difference in position is always 2. Double it to find the number.
So 18 - 7 = 11. 2 * 11 = 22.
Jun 03, 2013

Good teaser BTW.

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