Raise your hand if you’ve ever faced down the knitting math monster and lost. Anyone?
You can be cruising along, feeling pretty fly. The end is in sight. You’re SO close, you can almost taste the glory. But then, wham! You run into this:
“Pick up a multiple of 5 + 3 and begin working ribbing as follows…”
A multiple of 5 + 3? Huh?
It seems like basic arithmetic, but even easy math can get a little murky if you’re not sure how to apply it to your knitting project. Here’s a quick and easy primer to guarantee that you can always (ALWAYS) determine the right stitch multiple for your sweater ribbing (or any other pattern that requires you to have a specific multiple of stitches to work out evenly).
Why do we use a stitch multiple?
There are many reasons we may need a specific stitch multiple, but one of the most common is for ribbing. Ribbing (and other pattern stitches based on a repeated stitch count) requires a specific number of stitches so that the repeats can be worked evenly. In some cases, as with a button band or bottom ribbing on a hand knit cardigan, we may want the ribbing to start and end symmetrically. For example, if we’re working a ribbed pattern of [k3, p2], we would want to start with a k3 and end with a k3 on the other side so that both edges are the same. The repeat is 5 stitches (k3 + p2 = 5) but we need an additional 3 stitches at the other end to complete the symmetry. In this case, the pattern would say you need a multiple of 5 + 3.
So, how do we know if we have the right multiple?
The easiest way to do this is to start by picking up the stitches as it seems appropriate based on your project, without worrying about the number of stitches just yet. When you’ve picked up your stitches, count them and then do the math backwards to see if you have the right multiple. It might look something like this:
Let’s say you picked up 154 stitches and you need a multiple of 5 + 3. Let’s work backwards:
Step One: 154 – 3 = 151 (We start by subtracting the 3 stitches based on the part of the equation in bold above.)
Step Two: 151 divided by 5 = 30.2 (We take the result from Step One and divide that number by 5 – for the multiple of 5.)
This doesn’t work out evenly, which means that 154 is not a multiple of 5 + 2.
We know that our multiple of 5 goes into the number of stitches we picked up at least 30 times evenly, because our math says it goes in 30.2 times. If we were to work those numbers the other direction and take 30* x 5, we would get 150 stitches. This is an even multiple of 5. We also know that we need a multiple of 5 plus 3 more stitches, so 150 + 3 would be 153.
*If the number had been 30.5 or larger, I would have rounded up to 31. Since it was 30.2, I rounded down to 30.
You picked up 154 stitches, which wasn’t an even multiple of 3. But if you were to eliminate one stitch and leave yourself just 153 stitches, then you would have an even multiple of 5 + 3. You can check your work like this:
153 – 3 = 150
150 divided by 5 = 30
Let’s try another one, with the same goal of having a multiple of 5 + 3.
This time we’ve picked up 167 stitches.
167 – 3 = 164
164 divided by 5 = 32.8
The result is not an even multiple of 5 + 3. We’ve learned that 5 goes into our number of stitches 32.8 times. Since 32.8 is closer to 33 than it is to 32, we will work backwards using 33 to see what stitch count we would need in order to have the right multiple of stitches.
33 x 5 = 165
165 + 3 = 168
We picked up 167, but we need one extra stitch in order to have a multiple of 5 + 3.
- Pick up the stitches as it seems appropriate.
- Take the number of stitches you picked up and subtract the number at the end of the stitch multiple you need. In this example (multiple of 5 + 3), the number is 3. (If you were to pick up a multiple of 4 + 2, then you’d use the number 2 here.)
- Take the result from #2 and divide it by the primary part of the multiple. In this example (5 + 3), that means dividing by 5. If your multiple was 4 + 2, then you would divide this portion by 4.
- If the end result is a whole number, then hooray! You have the correct multiple.
- If not, round your result to the nearest whole number and work backwards to determine how many stitches you need to lose or gain in order to end with the appropriate number of stitches.
- If you have a few too many or too few, you can adjust this as needed by either picking up again, or – if you’re working with live stitches – simply working a couple of strategic decreases or increases on the first row until you have arrived at your destination.
It’s a bit math-y, but knowing how stitch multiples work can make life a little easier when you need them.