A home owner uses 4.00 $\times$ 10³ m³ of methane (CH₄) gas, (assume CH₄ is an ideal gas) in a year to heat his home. Under the pressure of 1.0 atm and 300 K, mass of gas used is x $\times$ 10⁵ g. The value of x is __________. (Nearest integer)

(Given R = 0.083 L atm K^$-$1 mol^$-$1)