Bob Umlas has a new book out. https://www.mrexcel.com/products/cool-excel-shit/ While I was working on indexing and layout of the book, I learned a lot of new Excel techniques, including this cool way to interpolate values.
If you enter a starting value in A1 and and ending values in A22, select A1:A22 and use Fill Series. Excel will automatically calculate the step value to create a perfect line.