Scientific notation

8.4/2.1=4. -6-13=-19.

The answer is 4*(10^-19), or 0.0000000000000000004.

$${\mathtt{8.4}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{{\mathtt{\,-\,}}\left({\frac{{\mathtt{6}}}{{\mathtt{2.1}}}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{{\mathtt{13}}}\right)} = {\mathtt{0}}$$