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# Is there a method to calculate........

01-20-2016, 02:25 AM
#1
Junior Member

Join Date: Jul 2014
Location: Kwazulu Natal, South Africa
Posts: 265
Is there a method to calculate........

Is there a calculator or basic method of working out how many different combinations of HST's you can make from a set number of fabrics, for instance 12 fabrics? I am useless at maths and my brain goes into overdrive just trying to figure it out
01-20-2016, 02:35 AM
#2
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Join Date: Oct 2010
Location: dayton OH
Posts: 1,911

i think 144.....12 x 12...........
01-20-2016, 03:25 AM
#3
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Join Date: Nov 2010
Location: Southern New Jersey USA
Posts: 1,473

The first fabric can be paired with 11 others, the next one with 10 others, the next with 9 etc. that is if you are looking for unique combinations.
01-20-2016, 05:26 AM
#4
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Join Date: Dec 2010
Location: Michigan
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Bjchad is correct. Start with 1, add 2 to that, then 3 etc. stop when you get to 1 less than the number of fabrics you have.
So lets say you have 6 fabrics. the number of unique HSTs would be 1+2+3+4+5 (the last number is the number of fabrics you have 6 minus 1 = 5).
01-20-2016, 05:33 AM
#5
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Location: Southern California
Posts: 19,131

Something keeps ring in my brain. I think it is 132 but I could be wrong. One fabric becomes your main fabric and you will get 11 different HSTs. When you finish the quilt, tell us the answer.
01-20-2016, 07:33 AM
#6
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Join Date: Jan 2009
Posts: 4,688

It's called permutations and combinations in the math world. Permutations are where order matters, combinations are where it doesn't.
http://betterexplained.com/articles/...-combinations/

In your HST example, order doesn't matter, so it's a combination. And specifically how many combinations of r objects (2 in this case) from a set of n objects (12 in this case). Without getting into too much detail or terminology, the answer is 66.
12 · 11 ÷ 2 · 1 = 132 ÷ 2 = 66

Another example: if you wanted to know the number of different four patches you could make with 20 fabrics, it would be:
20 · 19 · 18 · 17 ÷ 4 · 3 · 2 · 1 = 116,280 ÷ 24 = 4,845

Have fun!

Last edited by ghostrider; 01-20-2016 at 07:37 AM.
01-20-2016, 10:57 AM
#7
Super Member

Join Date: Oct 2010
Location: California
Posts: 1,726

I have a book: Quilters Reference Tool written by Harriet Hargrave et al

It has tables and yardage...takes the math out of piecing

http://www.amazon.com/Illustrations-...rriet+hargrave

Also this one, but I haven't seen it, just found it online
https://www.byannie.com/shop/product/math-for-quilters/
01-20-2016, 03:18 PM
#8
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Join Date: Jul 2014
Location: Illinois
Posts: 2,140

Are you counting each direction change? If so, you would have 300 possible combinations. If not, it's 75.
You need to add each consecutive number together to get the total. If you have 4 different layouts, then you need to also multiply the answer by 4.
12+11+10+9+8+7+6+5+4+3+2+1=75 | 75x4=300

Note: The above answer includes matching together 2 of the same fabrics (will look like a square of that fabric). If you don't want that option, get rid of the highest number.

11+10+9+8+7+6+5+4+3+2+1=63 | 63x4=252

01-20-2016, 07:41 PM
#9
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Join Date: Mar 2010
Location: greater NorthEast
Posts: 3,004

Yikes, now i know why i like scrappy quilts so much -- there is no math!!!
01-20-2016, 07:51 PM
#10
Super Member

Join Date: Aug 2013
Posts: 9,295

If one quilter boarded a train from New York to Chicago at 3:45 pm with 27 yards of fabric And a long arm, , and another quilter boarded a train from Omaha to Chicago at 2:30 pm with 13 yards and a Featherweight, how much chocolate would they eat in Paducah?
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