what is 2*10^-10/197

No disagreement with happy7, but if you did not mean that 197 to be the denominator of the exponent but rather you meant this:  (2x10^-10)/197, then the answer would be 1.015 x 10^-12.

Why don't you just enter the problem into a calculator and solve it for yourself?

$${\mathtt{2}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{{\mathtt{\,-\,}}{\frac{{\mathtt{10}}}{{\mathtt{197}}}}} = {\mathtt{1.779\: \!379\: \!465\: \!310\: \!911\: \!8}}$$