The activation number of a card is printed at the top of the card. This is the number that a player must roll for the card to take effect. A card may have a range of numbers instead of just one, for example the Bakery is activated on 2 to 3.
Activation numbers in the base game range from 1 to 12, with numbers greater than 6 achievable by using the Train Station. If the player has the Harbor from the Harbor Expansion, the player has the option to add 2 to their roll of 10 or higher, leaving the range from 1 to 14.