Help with decreasing stitches, keep to pattern

Hi, be really grateful if someone could help me understand decreasing stitches, keeping to pattern. I thought I had it worked out but I don’t. I’ve read lots of posts but they just don’t make sense to me.

I am on my third knitting project and I chose one categorised as easy but with a pattern - a baby’s jumper with repeating diamonds. I’m now at the armholes so starting to decrease stitches.

The pattern says
"Keeping patt correct, cast off 5 sts at beginning of next two rows …73 sts".

Then I have to dec on st at each end of row, then in every foll alt row.

I did a visual chart to help me work out the stitch I needed to start on after casting off but when I started knitting I realised that to cast off 5 stitches you need to effectively knit 6 stitches (at least that’s how it seems to me).

The two rows I need to cast off 5 are:

K5, *P1, K7, rep to * to last 6 sts, P1, K5
P4, *K1, P1, K1, P5, rep from * to last 7 sts, K1, P1, K1, P4

This is how I thought it would work:

Cast off 5, *P1, K7, rep from * to last 6 sts, P1, K5
Cast off 5, P1, K1, *P5, K1, P1, K1, rep from * to last 7 sts, P5, K1, P1

I know there’s a mistake in that because when I got to the end of the first row I could only do P1, K4.

I’m confused - does that mean the last stitch I knit to cast off should be in the pattern?

Thank you!!

Welcome to KnittingHelp!
You’re right that you have to use 6sts to cast off 5.
The important thing about these decreases is that you maintain the alignment of the pattern. The best way to do this is to look at the pattern on the previous rows and figure out which stitch should come next to keep the pattern correct. You can look anywhere in the pattern but usually the first dozen sts or so are enough. Then count backwards to the beginning of the row, naming the sts as you go.
Don’t worry too much about what to do with that last stitch remaining on the needle from the bind off. That’ll probably fall into the seam anyway.

If making a chart helps, go ahead and use it. The first two rows would be:
Cast off 5, K7, *P1, K7, rep to * to last 6 sts, P1, K5
Cast off 5, K1, P5 *K1, P1, K1, P5, rep from * to last stitch K1

Thank you so much for your help! I’m still learning how to read the stitches and because it’s an 8 row repeating pattern I’m finding it a bit complicated - I’ll have another go now!

Try just looking at the previous row. This will get easier with practice and is a skill well worth working at.