using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        List<float> numbers = new List<float> 

        { 

            0.0f, 

            1.0f, 

            0.1f,

            0.25f, 

            0.125f, 

            0.0625f, 

            0.03125f,

            25704f,

            1.000002f, 

            10.00002f, 

            100.0002f, 

            1000.002f, 

            10000.02f, 

            100000.2f, 

            3.14159f, 

            -1.1112f 

        };

        string json = JsonConvert.SerializeObject(numbers, Formatting.Indented, new FormattedFloatConverter());

        Console.WriteLine(json);

    }

}

​

class FormattedFloatConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return (objectType == typeof(float));

    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

        writer.WriteRawValue(((float)value).ToString("0.########"));

    }

    public override bool CanRead

    {

        get { return false; }

    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

        throw new NotImplementedException();

    }

}

​