This study explored whether kindergarteners who had yet to learn about multi-digit numbers at school could automatically process the underlying magnitudes, i.e., place-values, represented by the digits in a multi-digit number. A place-value Stroop task showed a pair of price tags in each trial. Each price tag contained a three-digit number, of which only one digit was visible. Children were asked to decide which price tag contained the physically larger digit. Results showed that both accuracy and reaction time were affected by place-values of the digits when the digits were sufficiently far apart in terms of decimal distance. Our findings suggest that young children are capable of activating and comparing place-values automatically, even before being formally introduced to the place-value concept.