FRACTIONS may be written as the ratio of two whole numbers, but that’s not how our brains process them. Instead it seems we respond to fractions directly, without processing whole numbers along the way. This suggests that kids, who often dread fractions, could be taught them more intuitively.

Previous tests have shown that specifc groups of neurons respond to different whole numbers, with the number one altering the firing patterns of different neurons than the number three. Now Simon Jacob and Andreas Nieder of the University of Tübingen in Germany have shown that we have fraction-specific neurons too.

The …