How many sulfur atoms are there in 3.5 mol of sulfur? express your answer using two significant figures?

Elemental sulfur has a many allotropic modifications.
1) If we use formula S, answer is:
N(S) = n(S) · Na.
N(S) = 3,5 mol · 6·10²³ 1/mol.
N(S) = 2,1·10²⁴ sulfur atoms.
2) If we use formula S₈, answer is:
N(S) = 8 · n(S₈) · Na.
N(S) = 8 · 3,5 mol · 6·10²³ 1/mol.
N(S) = 1,68·10²⁵ sulfur atoms.
Na - Avogadro number.

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