You're asking about the number of neutrons in the Aluminum atom (Al). Here's how to figure that out:

* Atomic Number: Aluminum has an atomic number of 13. This means it has 13 protons.

* Mass Number: The most common isotope of Aluminum has a mass number of 27.

* Calculating Neutrons: Neutrons are found by subtracting the atomic number from the mass number: 27 - 13 = 14 neutrons.

Therefore, the most common isotope of Aluminum (Al-27) has 14 neutrons.