they could have simply asked their grandparents, as a similar phenomenon described the previous ninety years. inflation in the united states is generally recognised to have been greater from 1913 to 1999, but not by as much as the often-disputed '90%' figure would have you believe. (probably it was about twice as great in the 20th century as the 19th century, though i'm saying that offhand without looking at the best data.

more to the point, very few people held dollars outside of interest-bearing accounts.