# How many carbon atoms are there in a 26-carat diamond?

The carat represents a mass of $0.200 \cdot g$, and is a measure commonly used for gemstones.
So, $\text{moles of carbon}$ $=$ $\frac{26 {\text{ carat"xx0.200*g*"carat}}^{-} 1}{12.011 \cdot g \cdot m o {l}^{-} 1}$.
We mutliply this molar quantity by $\text{Avogadro's number } , 6.022 \times {10}^{23} \cdot m o {l}^{-} 1$, to give the number of carbon atoms.