A steel rod with $y = 2.0 \times 10 ^ { 11 } \mathrm {~N} \mathrm {~m} ^ { - 2 }$ and $\alpha = 10 ^ { - 5 } { } ^ { \circ } \mathrm { C } ^ { - 1 }$ of length 4 m and area of cross-section $10 \mathrm {~cm} ^ { 2 }$ is heated from $0 ^ { \circ } \mathrm { C }$ to $400 ^ { \circ } \mathrm { C }$ without being allowed to extend. The tension produced in the rod is $x \times 10 ^ { 5 } \mathrm {~N}$ where the value of $x$ is $\_\_\_\_$.