+The **mass number** (A) is the total count of [protons](/wiki/Proton) and [neutrons](/wiki/Neutron) within an atom's [nucleus](/wiki/Nucleus). This crucial integer value dictates the atom's approximate mass, differentiating [isotopes](/wiki/Isotopes) of the same element.
+## See also
+- [Atomic Mass](/wiki/Atomic_Mass)
+- [Atomic Number](/wiki/Atomic_Number)
+- [Nucleon](/wiki/Nucleon)
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