When butane gas is pumped into a metal bottle, it is compressed greatly, normally so that 1.67 litres contains 1kg of gas. We can use this to work out the pressure at which the butane is stored.
The empirical formula for butane is  {jatex options:inline}C_4H_{10}{/jatex}, so that 1 mol of butane has a mass of  {jatex options:inline}12 \times 4 +1 \times 10=58 \; g = 0.058 \; kg{/jatex}
In 15 kg butane there are  {jatex options:inline}\frac{15}{0.058} = 258.6 \: mol{/jatex}  A 15 kg butane bottle contains 15 kg butane, so  {jatex options:inline}15 \times 1.67 \: litres = 25 \times 10^{-3} m^3{/jatex}
Take the temperature as  {jatex options:inline}25^{\circ} C \equiv 298^{\circ} K{/jatex}
Now use the ideal gas equation  {jatex options:inline}pV=nRT{/jatex}
{jatex options:inline}p= \frac{nRT}{V} = \frac{258.6 \times 8.314 \times 298}{25 \times 10^{-3}} = 2.563 \times 10^7 Pa{/jatex}
Atmospheric pressure is about  {jatex options:inline}10^5 \; Pa{/jatex}  so this is equivalent to about  {jatex options:inline}\frac{2.568 \times 10^7}{10^5} = 256.8 {/jatex}  times atmospheric pressure.