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You can enter your youtube videos in the DIY Halloween Contest. Just add them to the DIY Halloween Contest Group. Here are some of the videos that we have received so far.

Pumpkin Carving Robot DIYHalloween

Toy Soldier

Halloween Haunt 2006 Final Look

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## 12 Replies

Goodhart (author)2007-10-24

Well, for 6 eyes and 3 noses first off we get a permutation of 120. But to plug 120 into the formula 120P3 = 120! over (120-3)! it becomes a little more difficult to solve.

fungus amungus (author)2007-10-24

Whoa! You just went too far and are making it too complicated.

Kiteman has it right with 6 x 6 x 3 x 3. You get a permutation of 120 if you have 6 non-repeating possibilities and 3 spots to put them in, but that doesn't make sense and would make for a funny-looking face.

Here you have four spots and each spot has 6 or 3 options, assuming that you're going to put the mouth in the mouth spot and the nose in the nose spot.

So 6 left-eye possibilities times 6 right-eye possibilities and so on.

And by the way, 120 choose 3 would be simply 120 x 119 x 118.

Goodhart (author)2007-10-24

ok, been a loooong time since I saw any of that stuff. Thank you for straightening me out there.

Kiteman (author)2007-10-25

See? Leave the fiddly stuff to the young folk - their fingers are more nimble.

Goodhart (author)2007-10-25

Ok, yeah the fancy stuff...I will stick to doing normal math then unless I am sure of myself ;-)

Brennn10 (author)2007-10-25

That carving robot is amazing! At first I thought it was fake, but it is pretty awesome. Can you have it carve different types of faces?

Kiteman (author)2007-10-24

Love the robot - I hope they cleaned the tools before the next shift came on...

Lizardo (author)2007-10-24

Thanks K -
I had a lot of dreams I would have liked to implement that I never had time to. I wanted to program multiple faces, but then I realized that since I programmed each of the facial features to be a separate subroutine that a multitude of faces was possible from the same amount of programming! You could have a touchscreen where the user could cycle through the available shapes, then hit the "carve" button when they were happy with their choices.

Help me with the math people! how many different ways could you arrange the features from 3 faces? (6 eyes, 3 noses, 3 mouths)

[8^}>]

Kiteman (author)2007-10-24

Er...

6 left-eye options x 6 right-eye options x 3 noses x 3 mouths = 324 faces

...?

Goodhart (author)2007-10-24

Ok, so where did I go wrong in my thinking :-(

Kiteman (author)2007-10-24

Hey, I could be wrong - I haven't done permutations and combinations for years. Let's wait for the high-schoolers to correct us, shall we?

Goodhart (author)2007-10-24

well, the formula is nPr = n! over (n - r)!