How many grams are in 12.4*10^15 atoms of neon?

Well I know that $6.022 \times {10}^{23}$ atoms of neon have a mass of $20.18 \cdot g$. How do I know this?
And thus the mass of $12.4 \times {10}^{15}$ $\text{neon atoms}$ $=$
$\frac{12.4 \times {10}^{15}}{6.022 \times {10}^{23} \cdot m o {l}^{-} 1} \times 20.18 \cdot g \cdot m o {l}^{-} 1$ $=$ ??g