Question:

I am knitting an infant dress. The pattern reads decrease 39 stitches evenly across the row. I have 131 stitches. How do I do this evenly?

Answer:

It doesn't have to be perfectly evenly, as the numbers won't allow. 

Before we do some math it would be good to determine the type of decrease that the pattern is looking for. Often at the beginning of the pattern it'll say something like, "Slip all sts as if to knit. Decrease with k2tog." If it doesn't have that, it may say in the pattern. The most common types of decreases are
1. k2tog (knit two together, which means to slip your needle into two sts and knit as if one)
2. sl1 k1 psso (Slip one, knit one, pass slipped stitch over)
3. ssk (Slip, Slip, Knit--slip one st, slip a second st, then stick your left needle into the two sts you just slipped and knit them off that way)

These different ways of decreasing give a different twist to the stitches, which makes them all look slightly different. If your pattern does not specify which way to decrease, you can assume they want you to k2tog.

And now, a little math
Subtract 39 from 131 (131-39=92)
At the end of this decrease row you are going to want to end up with 92 stitches.

Next question is, "How often do I decrease?"
Divide 131 by 39 (answer=3.35897...)

So you know you are going to decrease just about every 3rd st. Or, in other words, you are going to take just about every 3 sts and turn them into 2 sts. 

Our next question is, "What would happen if I worked k2, k2tog across the row 39 times?"
39 X 3=117 (So we know you would end up on st 117)
131 - 117=14 (And you would have 14 sts left over.)
Somehow you have to distribute those 14 extra sts evenly across the row as you decrease.

You are going to decrease 39 times. 
39 divided by 14 = 2.7
So just about every other decrease you will want to add an extra st.

Let's try it:
Start working across the row as follows: k2, k2tog, k3, k2 tog, rep.

When you get halfway across your row, stop and count your stitches. Is it coming out okay? This is the spot to adjust by adding an extra st between your decreases, or take out an extra. 

Don't freak out if you have to take your whole row out and start again. Ripping is part of good knitting! --Remember, it's suppossed to be enjoyable.

And good luck. 

Connie Delaney
SpinCraft Patterns
www.spincraftpatterns.com