.net - Get String Name from Enum in C#

I have declared enum as below

public enum State
    {
        KARNATAKA = 1,
        GUJRAT = 2,
        ASSAM = 3,
        MAHARASHTRA = 4,
        GOA = 5
    }

From external sources, I get the State values as either 1 or 2 or 3 or 4 or 5.

Based on the value i get, I need to look up this enum and get its string.

For Ex: If the input value is 1, I need to return KARNATAKA as string. Similarly, If the input value is 5, I need to return GOA as string.

Is there a easy way to get the string with out using CASE or IFELSE.