Reading gauge on a lace pattern
I'm knitting the Vilma Top by Gregoria Fibres. I'm using Drops Nepal on 4mm needles. The pattern asks for 21 stitches per 4 inches/ 10 cms.
The pattern repeat is 24 stitches. I have knit a garter border with an additional stitch of stockinette on either side to account for any distortion caused by the garter stitch and to make it easier to see where my pattern begins. 32 stitches cast on (3 garter, 1 stockinette, 24 pattern, 1 stockinette, 3 garter).
I have already looked up how to do this but wanted to run this by some extra eyes just in case! Sometimes I'm so confidently wrong in my maths.
So the pattern measures 4.5 inches, sometimes ever so slightly more.
So is it 24÷4.5 = 5.33 stitches per inch, then × 4 = 21.3?
When I do it in cms its 11.5 cms. So 24÷11.5=2.08 × 10= 20.8 stitches per 10 cms.
So either 21.3 stiches per 4 inches or 20.8 stitches per 10cms.
My two questions I guess are: is my maths correct and this is how you calculate gauge with lace? And is this hitting gauge?