2. In the USA, the date is typically written as the month number, followed by the day number, and then the year. In Europe, however, the day comes first, followed by the month and the year. How many days in a year cannot be read unambiguously without knowing which format it is written in?
2. It is clear that these are the days whose date can be the number of the month, i.e., takes values from 1 to 12. There are such days $12 \cdot 12=144$. However, the days where the number matches the month are unambiguous. There are 12 such days. Therefore, the number of days sought is $144-12=132$.