@Natasha_Jay A logarithmic scale with some discontinuities. Note that I actually don't know exactly my age, as I don't celebrate birthdays and I don't find it relevant in my daily chores. Then, from time to time (rarely indeed) I see someone I knew in my early years, and I think "wow, they're old". At that point I have to resort to a calculator to desume my age - because with mental calculation the result is "weird". Human brain is unfit for time math, we can't even add up the secs in a min