The article uses this kind of calculation to show the difference between labor productivity growth of 1.4% versus 2.5%. At a growth rate of 1.4% per year, labor productivity (and wages) will double every 50 years because 70 divided by 1.4 is about 50. A growth rate of 2.5% will double labor productivity every 28 years because 70 divided by 2.5 equals 28.
If the average employee compensation grew at the rate of 3.5% per year, how many years would it take for it to double?