How to 'knit up'

Hi everyone!
I’ve finally finished knitting the pieces for my granddaughters cardigan, thanks to salmonacs’ help with the sleeves! However I now have a problem with the button band. I have to knit up a certain amount of stitches to the start of the front slope. I get what I have to do, but my problem is that there are 88 rows for example on this piece, and I have to pick up 71stitches. How do I work out how to pick up 71 stitches, evenly?! My maths is generally good, but I’m struggling to work this out!! Is there a magic formula?!
Thanks in advance!!

The formula I use is this:

Number of rows you have (88), subtract the number of stitches you need to pick up (71), then divide that difference (17) into the number of stitches to pick up (71/17). That tells you how often to skip a row when picking up stitches (4.17 rows). In your case, pick up 4 stitches on consecutive rows, skip the next row and repeat to the end.

Another way is to use locking stitch markers to subdivide the area where you need to pick up stitches. Mark the center, then mark the center of each 1/2. This makes 4 equal sections. Dividing 71 by 4 is just shy of 18. You’ll need to pick up 18 stitches in 3 of the marked sections and 17 in the 4th.

Thank you Metylda! I had that formula idea in my head, but just couldn’t make it work! So I pick up 4, skip 1, 17 times, makes 68 picked up, and 85 in total, then pick up 3, so 71 picked up, 88 in total, perfect!
Thanks so much!!

You’re very welcome. Glad I could help.