64 2/3 / ( 1/8) -1/3

This IS a calculator site.

Anyway:

$${\frac{\left({\mathtt{64}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{2}}}{{\mathtt{3}}}}\right)}{\left({\frac{{\mathtt{1}}}{{\mathtt{8}}}}\right)}}{\mathtt{\,-\,}}{\frac{{\mathtt{1}}}{{\mathtt{3}}}}$$  

$${\frac{\left({\mathtt{64}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{2}}}{{\mathtt{3}}}}\right)}{{\mathtt{0.125}}}}{\mathtt{\,-\,}}{\frac{{\mathtt{1}}}{{\mathtt{3}}}}$$

64+2/3  64.66667

$${\frac{{\mathtt{64.666\: \!666\: \!666\: \!666\: \!666\: \!7}}}{{\mathtt{0.125}}}}$$ 517.3333333333333336

517.3333333333333336-1/3  517.0000000000000002667 517