The answer is 1.63 × 1024 atoms Fe.
Avogadro's number is the number of units (atoms, molecules) in 1 mole of substance: 6.023 × 10²³ atoms per 1 mole
So, how many atoms are per 2.70 moles:
6.023 × 10²³ atoms : 1 mole = x : 2.70 moles
x = 6.023 × 10²³ atoms * 2.70 moles : 1 mole
x = 16.3 × 10²³ = 1.63 × 10 × 10²³ = 1.63 × 10²⁴ atoms