I love to knit cardigans, but I dread seeing the instructions "make X buttonholes evenley spaced". MATH!!! AGGGHHH.
Today while I was mustering up the strength to calculate the placement of the buttons/buttonholes on my Kauni Cardigan, I remembered I had purchased a SimFlex Sewing Gauge a while ago. This handy tool is designed to easily mark buttonholes (among other uses). "Simply lay it over your garment and expand it to the desired length for perfectly measured equal distances and accurate spacing from 3/8 inch to 3 3/8 inch. Expands to a total of 24 inches."
In no time, I had 7 perfectly spaced buttonholes and I am just finishing my cardigan! Hooray! This little tool runs from 15-20. and I got mine at my local sewing/yarn shop. It's available on the web too (I put a link to one place that sells it, no affiliation etc). Well worth having in one's knitting tool box!