Have you always wondered how to resize a quilt block or a favorite appliqué pattern?
Here's some good information from Robin Strobel, an expert quilter and an experienced teacher, technical editor, illustrator, and author, who has the mathematics down pat! She says it'll be a breeze if you'll just remember this quote, "ya start with whatcha want, and ya divide it by whatcha got."
You want to reduce a 12" finished block to a 10" finished block (always use finished dimensions).
Example: 10 (whatcha want) divided by 12 (whatcha got) = .833333 (always move the decimal 2 places to the right) so 83.3% is the percentage you would enter into your copy machine.
Lets say that you have an appliqué pattern for a 6" x 7 1/2" heart, and you decide you'd like to make it at least 8" wide, but you're clueless how tall that will be.
Example: 8 (whatcha want) divided by 6(whatcha got) = 1.3333. So you will enlarge the picture by 133.3. Then take the height 7 1/2 and multiply it by the same percentage to find out the new height. 7.5 x 1.333 = 9.99975. The heart will be about 10" tall.
One way to check that you did the math correctly is to remember the following. The proportion number will always be greater than 1.000 if you're enlarging something and will always be less than 0.999 if you want to make something smaller.
So, there it is, a bit of knowledge to allow you to resize your favorite pattern, up or down!