How many atoms are in 45.6 g gold, au

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles.

45.6 g Au ( 1 mol / 196.97 g ) (  6.022 x 10^23 atoms / mole ) = 1.39x10^23 atoms Au