[Rounding off positions used in number comparisons]

In everyday situations, people round off multidigit numbers to what they consider an appropriate place. This study examined how many places people rounded to in a situation where they were required to choose between higher payments with long delays and lower payments with short delays. The payments were 4-digit numbers of yen and the ordinal sequences of the digits in the second, third, and fourth places were manipulated. In the compatible conditions, the ordinal direction in the second place of the low-order numbers was the same as that of highest-order numbers, for example 23xx and 48xx yen. In the incompatible conditions, the ordinal direction of the low-order digits was reversed, for example 28xx and 43xx yen. The results showed that rounding to a higher payment was more prevalent in the compatible conditions than in the incompatible conditions for the second place, but there was little effect in the third and fourth places. These results suggest that people compare the first two digits and make little reference to the third or later ones in rounding numbers.