C++ :: How To Overload Class Func With Outside Func While In Same Class

I have a class that has a method name the same as another method separate from the class and I am writing another class method in the class but want to call the outside method instead of the one in the class.

Is there a way I can overload the class method with the outside one?

Here is what the situation looks like :

Code:
class LongInt{
int digits() { /* find total # of digits of this object */
LongInt divide(const LongInt&); // this method is where I want to use the outside digits(int number) method
}
int digits(int number){ /*finds total digits of number */} T

he problem is when I call digits(number) inside the class, I get compiler error saying it doesn't take 1 arguments.