Multiplying the total number of moles by 6.02x10^23 will give you total number of atoms present. 6.02x10^23 is known as Avogadro's Number and is the approximate number of atoms in a mole.
Moles are used instead of total atoms out of convenience. It can be difficult to perform long-form calculations with large numbers. Because atoms are present in large quantities in experimental solutions and compounds, it would be tedious and inefficient to perform calculations using the total number of atoms.The mole is also useful because it is a constant value. Units such as liters and grams are dependent on physical quantities and do not consistently describe how many atoms are present. Moles are a used as a simplified ratio of total atoms to make consistent comparisons and calculations.
Avogadro's Number was not actually discovered by Italian physicist Amadeo Avogadro but is named after him based on his hypothesis that equal volumes of gases at constant temperature and pressure have the same number of particles. Austrian professor Josef Loschmidt was the first to estimate the number of particles in a substance, now known as the Loschmidt constant. French physicist Jean Baptiste Perrin was the first to use the term "Avogadro's Number," and the actual value along with the techniques used to determine it have changed over time.