express 9.1X10^-2 in standard notation?

$$9.1\times 10^{-2}$$

alright, the power is -2 

so you have to move the decimal point 2 places. The negative sign means that you have to move it in the correct direction so that the answer gets smaller.

so you jump the point over the 9 and then over the invisable 0 and you get   $$.091$$      I think it is a good idea to put a zero in front of the decimal point so that it is easier to read so I would leave the answer as 

$$0.091$$      

Does that all make sense.

$${\mathtt{9.1}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{-{\mathtt{2}}} = {\frac{{\mathtt{91}}}{{\mathtt{1\,000}}}} = {\mathtt{0.091}}$$