How would you calculate the mass number of an atom?

Related questions

• How do you find mass number of an isotope?
• What does the difference between the mass number and the atomic number tell us?
• Why is mass number a decimal?
• What type of radioactive decay produces no change in mass number?
• How is the mass number written?
• What is the nucleon number?
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• What does the mass number tell us?
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