calculating mass and atomic numbers

Atomic number ($Z$)

The number of protons found in the nucleus of an atom.

Mass number ($A$)

The total count of protons and neutrons located in the nucleus of an atom.

Calculation for the number of neutrons

$$\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$$

Number of electrons in a neutral atom

Equal to the atomic number ($Z$), which corresponds to the number of protons.

Subatomic particles located inside the nucleus

Protons and neutrons.