// Scilab code Exa18.18 : : Page-770 (2011)
clc; clear; 
m_sqr = 0.71;        // For proton, (GeV/c-square)^2
R_rms = sqrt(12)/(sqrt(m_sqr)*5.1);    // Root mean square radius, femto metre
printf("\nThe root mean square radius of charge distribution: %4.2f fermi", R_rms);

// Result
// The root mean square radius of charge distribution: 0.81 fermi