$9 \times 0.35 = 9 \times \frac{35}{100} = \frac{315}{100} = 3.15$
This reduces it to just calculating $9 \times 35$.
IMHO if you are taking the GRE, it is better to convert the decimal to the form $\frac{x}{100}$ and reduce the problem to simple multiplication of the first term and the numerator. Then, dividing by $100$ is easy.
I took the GRE general test recently.
Edit
$80 \times 0.35 = 80 \times \frac{35}{100} = 8 \times \frac{35}{10} = \frac{280}{10}$
Once again, you can simplify the problem to multiplication by the first term and the numerator.
IMHO this is the simplest, least error-prone, and fastest way for GRE questions involving decimals.