Don't name a local variable the same as the function

Before:

// Calculates the premium based on rate and months, and applies a discount
double calcPremium( double rate, int months )
{
   // Calculate premium
   double calcPremium = rate * months;

   // Provide 20% discount for 9 or more months
   if( months >= 9 )
      calcPremium -= calcPremium * 0.2;

   // Return premium
   return calcPremium;
}