Perfect numbers

using System;

using System.Linq;

​

public enum Classification

{

Perfect,

Abundant,

Deficient

}

​

public static class PerfectNumbers{

public static Classification Classify(int number){

​

    if(number < 1) throw new ArgumentOutOfRangeException(nameof(number));

    var result = Enumerable.Range(1, number / 2)

        .Where(i => number % i == 0).Sum();

    

    if(result < number) return Classification.Deficient;

    else if (result > number) return Classification.Abundant;

    else return Classification.Perfect;

}

}