> It’s common to rack up 4 hours or more of screen time a day on your phone. Here’s one way to see the cost of that: every 20 years, you lose 5 years of your waking time looking at your phone.

If you spend 4 hours/24 hours on your phone then every 20X you'll have lost 3.33... X.

I think the author is using year and waking-years but it doesn't parse well for me because you don't get close to 20 waking-years for every 20 years.