Thirtysomethings flex their number sense

Insight into quantities maxes out in adulthood and may influence math achievement

Even 6-month-old babies can rapidly estimate approximate numbers of items without counting. But surprisingly, an apparently inborn sense for numbers doesn’t top out until around age 30.

Number sense precision gradually declines after that, generally falling to preteen levels by about age 70, say psychologist Justin Halberda of Johns Hopkins University in Baltimore and his colleagues.