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#3532 Re: This is Cool » base-10 using -4 to +5 » 2005-09-04 03:27:20

Here is pi (to 30 places after the decimal) shown 
normally and pi in new Winter sytem.
I called it the Winter system because I like winter and
also you can remember that you get below zero temperatures
in the winter like the numbers used here.

3. 1 4 1 5 9 2 6 5 3 5 8 9 7 9 3 2 3 8 4 6 2 6 4 3 3 8 3 2 7 9
3. 1 4 2-4-1 3-4 5 4-4-1 0-2-1 3 2 4-2 5-4 3-4 4 3 4-2 3 3-2-1

You can obtain the above conversion just by working 
from left to right or from right to left on the normal 
number pi.  If you go right to left, it is very easy.  
Simply carry the 1 if a conversion to negative is made.
So starting at the end of the above pi, look at the 9.
Since 9 isn't allowed in the Winter system, you use need
to think ten minus one.  Nine in the Winter system is a
two digit number and is written 1-1.  A 1 in the ten's place
and a -1 in the one's place.  So you take the -1 and write it
down below the 9.  Then you carry the 1 from the ten's place.
Now we convert the next digit to the left seen above
and it is a seven.  Since we had carried a one, we add it to
the seven and get eight.  Then we convert eight to the Winter
system and think "eight is not allowed because it is above 5,
so eight is ten minus two".  So "8" is "1-2".  So write down
the -2 and carry the 1.  If you run across a case where you
carry a one onto a 9, then you think okay, ten, and ten is 
still 10 in Winter system, so write down zero and carry the 
one.  So that's my explanation of going from right to left
and converting from normal numbers to the Winter system.

If you go left to right you have to look ahead a few digits
to see what's coming next.  The explanation of that is
more complicated than going right to left, but all I think 
I should say is the following and let you work it out for
yourself if you want to do it that way.

A "0" digit may remain "0" or may change to "1". 
A "1" digit may remain "1" or may change to "2". 
A "2" digit may remain "2" or may change to "3". 
A "3" digit may remain "3" or may change to "4". 
A "4" digit may remain "4" or may change to "5". 
A "5" digit may remain "5" or may change to "-4". 
A "6" digit will change to "-3" or "-4".
A "7" digit will change to "-2" or "-3".
A "8" digit will change to "-1" or "-2".
A "9" digit will change to " 0" or "-1".

Good luck playing around with the new Winter number
system.  If you have any questions, just ask!

smile

#3533 Re: This is Cool » base-10 using -4 to +5 » 2005-09-03 01:29:21

1/7 is normally 0.142857 repeating.  Now it is 0.143-1-4-3 repeating!  I wonder what I'll find next?

#3534 Re: This is Cool » base-10 using -4 to +5 » 2005-09-02 20:07:07

I went to bed and then I had a great idea so I got back up and worked on this through the night.
I hope you like it as much as I do.   Imagine the possibilities! smile smile smile big_smile big_smile big_smile

Winter_multiplication_table.GIF

Here is an example comparing our number system to the new Winter number system.

  285
  x64
-------
18240


or in this new Winter number system we have

    3-2 5
  x 1-4 4
----------
   1 1 4 0
-1-1-4 0
 3-2 5
-------------
 2-2 2 4 0

#3537 Re: Jai Ganesh's Puzzles » Problems and Solutions » 2005-09-02 17:24:18

I guess 1/18 chance if they can't both be the same chess square.

#3539 This is Cool » snazzy multiplication table » 2005-09-02 16:07:28

John E. Franklin
Replies: 1

I thought some elementary school teacher might like this.
It's kind of nice I think.

mult.GIF

#3540 Re: This is Cool » The TV show Numb3rs and probability » 2005-09-02 16:03:48

But it's not about changing your mind, it's what they have done.  They chose not to open the curtain with
the car for suspense.  See what I mean.  I don't know the math behind what I'm saying though.

#3541 Re: This is Cool » The TV show Numb3rs and probability » 2005-09-02 15:47:25

I think that you should switch because they didn't open the goat curtain at random, they may have specifically
have chosen the goat, not the car behind the other curtain.  I think I heard this long ago, some question
analogous to this one.  tongue

#3542 This is Cool » base-10 using -4 to +5 » 2005-09-02 14:30:04

John E. Franklin
Replies: 8

I just thought this up.  Use base-10 but limit yourself to the digits negative
four to positive five.  In the left column below I am counting from 1 to 20.
In the right column I show the square of the number.

  1       1
  2       4
  3     1-1
  4     2-4
  5     2 5
1-4     4-4
1-3     5-1
1-2   1-4 4
1-1   1-2 1
1 0   1 0 0
1 1   1 2 1
1 2   1 4 4
1 3   2-3-1
1 4   2 0-4
1 5   2 2 5
2-4   3-4-4
2-3   3-1-1
2-2   3 2 4
2-1   4-4 1
2 0   4 0 0

wink

#3543 This is Cool » tetrahedron: angle from center » 2005-09-02 11:01:54

John E. Franklin
Replies: 5

When I was learning about angles of atoms in crystals in Chem 1 at WPI in Worcester, Massachusetts in 1986, the
tetrahedron was one of the 3-d configurations.  I don't remember why, but they wanted us to figure out the
angle from the center of the tetrahedron to any two of the vertices.  So I spent all weekend on that
and used complicated navigation formulas to get an answer.  Then I tried to figure out if this number
for the answer could be expressed simpler, and finally I found out the easy way.

I'll post the answer sometime later to give folks a chance to try it out themselves.  So to restate the problem, it
is the same as the angle between any legs on a tripod, if the tripod and a vertical rod form a tetrahedron.
Remember all four sides of a tetrahedron are equilateral triangles.

#3544 Re: Help Me ! » Find an equation from more than 2 coordinate point » 2005-09-02 04:06:58

If you graph the four points given, one could assume it might be a parabola opening downward.
If so, then y = ax² + bx + c.
I worked it out and in fact it can be a parabola.  So start substituting the points into x and y in y = ax² + bx + c.
Then you have four linear equations with variables a, b, and c.
Play around with those and you get the answer.   y=-7x² + 43x - 41   Have fun working it out.  If you need more help, just ask!

#3545 Re: Help Me ! » Pyramids Question » 2005-09-02 03:11:23

I get the same result as nvidura.  There are five views: top view (easy),  south, west, north, and east views (harder).

So to calculate the south view vertical number of blocks:
You combine the bottom row with the top row making 101 blocks.  Then you combine the 2nd row with 2nd row from the top, this also is 101 blocks (99 + 2).  So I drew a small one that started out with three, but it was odd, and it wasn't analogous to 100 on the bottom.  Then I redrew four on bottom and realized the number of pairs of 101 would be 50.   So that's how it goes.


To compute the top surface area:
If you walk up the pyramid, each step is half a block forward from the next; they overlap.  But you don't need to worry about
that if you just look at the whole pyramid from an airplane, and just compute the area of the overall square.


Units:
and you can use 0.63 meters and 0.97 meters right off the bat to make things a little easier.

#3546 Re: Introductions » Hi everyone! » 2005-09-01 10:00:06

Welcome to the forum.  I've only been here a few days, myself!

#3547 Help Me ! » overflowing base-2 ? » 2005-09-01 09:50:42

John E. Franklin
Replies: 2

Does anyone have a name for
a number system where the
digits can be values larger
than the base?  Here is an
example using base-2 places
but filling them with digits
up to 9.  Each four digit
number shown below has a
value of 68 in base-10.

8's  4's  2's  1's  place

7    3    0    0  roll

6    3    4    0  neutral

4    5    7    2  yikes

1    9    9    6  wink

8    1    0    0  lol

1    9    8    8  smile

#3548 Re: Help Me ! » probability, drawing cards from a deck » 2005-08-31 13:27:32

I would be interested in knowing how to solve this directly, however, without iterating the possibilities and choosing the
easy ones:  3 black or 3 red

#3549 Re: Help Me ! » Dimensional Arrays? » 2005-08-31 13:21:50

Or another example would be to convert one foot into 12 inches.

(1 foot/1) multiplied by (12 inches/foot)

The foot in the numerator cancels with the foot in the denominator, so the units of the answer is inches.

#3550 Re: Help Me ! » probability, drawing cards from a deck » 2005-08-31 06:50:03

B = black,  R= red

BBB  .1176470588  Find this one first: (26/52) * (25/51) * (24/50)
BBR
RRB
RRR .1176470588

Then All four combinations must be 100% so double .1176470588, subtract it from 1, and cut it in half! smile

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