Can this simple percentage calculator be further optimized? public double getValueWithPercentage(double number, double percentage)
{
    return number + ((percentage / 100.0) * number);
}


Are there any tricks to optimize this simple code?
Since floating-point divide is sometimes a little slower than multiply (and never faster, AFAIK), I'd write your function like this:

public double getValueWithPercentage(double number, double percentage)
{
    return number * (1 + percentage * 0.01);
}