The values of conductivity of some materials at 298.15 K in Sm^-1 are 2.1 × 10^3, 1.0 × 10^-16, 1.2 × 10,3.91,1.5 × 10^-2, 1 × 10^-7, 1.0 × 10^3. The…

The values of conductivity of some materials at $\displaystyle 298.15 \mathrm{~K}$ in $\displaystyle \mathrm{Sm}^{-1}$ are $\displaystyle 2.1 \times 10^3$, $\displaystyle 1.0 \times 10^{-16}, 1.2 \times 10,3.91,1.5 \times 10^{-2}, 1 \times 10^{-7}, 1.0 \times 10^3$. The number of conductors among the materials is $\displaystyle \_\_\_\_$.