The scores vary by age group, with young people generally performing much better than older people within almost every country.
Interestingly, it’s the younger cohorts who are dragging U.S. numeracy scores down. Americans aged 55 to 65 did okay, if not exactly spectacularly, when compared with their counterparts in other countries. But among those aged 16 to 24, Americans scored the worst of any country, and among those aged 25 to 34, Americans had the second-lowest score.
Here’s a sample question from the numeracy assessment, to give you a flavor of what the test measures: