On 4/9/2017 9:20 AM, wrote:
You don't need math AT ALL to get evenly spaced marks. Get some elastic tape from a sewing center. Mark it every two inches. Put one of the marks where you want the first hole to be. Stretch it to get the desired number of holes with the last hole being where you want the last hole to be.
Done.

https://www.youtube.com/watch?v=WtlPfXVjWKw



Great for dress making, I guess.