# Why is there an atomic mass unit?

We could report atomic masses with units of grams or kilograms. And thus an ""^1H atom has a mass of $1.67 \times {10}^{-} 24 \cdot k g$ or $1.67 \times {10}^{-} 21 \cdot g$. This is a bit inutile given that the we have to go thru the rigmarole of exponents, and even here they are a pain to write down and format....
Historically, while the mass of an hydrogen atom could not be experimentally measured … its mass could be inferred by reference to the mass of other atoms and molecules... and historically $1 \cdot \text{amu}$ was $\frac{1}{12} \cdot \text{th}$ the mass of the ""^12C $\text{isotope..}$