How is the mass number of an atom calculated

Answer 1

The mass number of an atom is calculated by adding the number of protons and neutrons in the nucleus of the atom. The mass number is often represented by the letter "A". Protons are positively charged particles found in the nucleus, and neutrons are neutral particles also found in the nucleus. Electrons, which are negatively charged particles, are not included in the calculation of the mass number because their mass is much smaller compared to protons and neutrons.