Remember that guy in the tenth grade who would torment your math teacher by asking, “When are we ever going to use this crap?” Or perhaps you grew up in a nicer neighborhood where that guy said, “When are we ever going to use this stuff?”
I’m here to tell you, ladies and gentlemen, that I am USING THAT STUFF. I have just USED IT. I have braided that math into a nice little charm bracelet for my wrist.
To whit, check it. What you are about to see has just made my brain hurt so bad that I think I need a lie-down. Which is fitting, since it’s midnight.
What the WHAT?, I can hear you thinking. What on earth is that? That, friends, is the set of calculations — that I programmed into Excel — required to figure out a set-in sleeve on a sweater. There are simpler sleeves that have squarer shapes (read: easier math), but this curvier sleeve fits the human body better.
To determine the shape of that sleeve, you have to use:
- the Pythagorean theorem
- parentheses to signal to Excel which operations get done first
- the vague memory that any number to the 1/2 power is the same thing as the square root of that number (I was super-dee-duper impressed with myself for remembering that one)
- and other whatnot
The numbers all look consistent with each other, so now I just have to check that they will fit an actual human body. That’s where the physics comes in — that is, the knitting.
If you’re thinking I’m pretty awesome right now — and I feel certain that you are — then let me give credit where credit is due. I’ve been learning how to calculate sleeve caps from a wonderful online class with Knitgrrl Studios. And I have learned a tremendous amount about how to make Excel do some of the work for you from the stupendously generous Marnie Maclean. Really, that woman deserves a medal.

