Final answer:
The number of protons in an element is equal to its atomic number, which is displayed above the element symbol on the periodic table and distinguishes one element from another.
Step-by-step explanation:
To calculate the number of protons in an element, you simply look at the atomic number (Z) of the element. The atomic number is the defining characteristic that differentiates one element from another and is always located above the element symbol on the periodic table. For instance, if an element has an atomic number of 6, that means every atom of that element has exactly 6 protons in its nucleus. Likewise, the atomic number also informs us about the number of electrons in a neutral atom of that element, because a neutral atom has an equal number of protons and electrons.