Can't calculate a tip or even balance your checkbook?
Take heart; maybe you can blame your brain -- specifically, the parietal cortex in the top back part of the head. And it could be a problem that has roots not in a failed arithmetic or "new math" lesson, but even earlier.
Recent findings indicate that how well 3-year-olds estimate quantities predicts their math ability in elementary school. Another study funded by the National Institutes of Health showed that the innate capacity to estimate is impaired in children who have a math learning disability.
The findings are so new that there's no widely accepted way to diagnose what's known as dyscalculia (dis-cal-KOO-lia), nor any set strategies for coping with it -- even though 5 to 8 percent of the population is thought to suffer from math learning disability. Consider it the mathematical partner to dyslexia, which impairs reading ability.
But while researchers have explored causes of dyslexia and developed strategies for compensating, the study of dyscalculia lags about 30 years behind. As a result, many people remain stymied by math.
The ability to estimate is an oft-tapped skill that, for example, helps waiting shoppers determine which checkout line is likely to move faster at the grocery store. And understanding the cause of the disability could lead to identifying children at risk of failing math and developing ways to help them.
"Children are being considered lazy or unmotivated, or not to have potential, when in fact they have a disability in processing numbers," said Michele M.M. Mazzocco, the lead researcher. "We need to learn how this can be overcome."
Mazzocco and colleagues at the Kennedy Krieger Institute in Baltimore began tracking 249 kindergartners in public schools in 1997. She found large differences in children's estimation skills. Even as ninth-graders, some who viewed a set of colored dots flashed briefly on a screen found it difficult to consistently estimate the number, or to distinguish quantities, such as 20 dots from 15 dots.
