using System;

using System.Collections.Generic;

using System.Text.Json;

using Newtonsoft.Json;

​

namespace Testing

{

    class Program

    {

        static void Main(string[] args)

        {

            decimal dec = 1234567.0M/8.9M;

            double d = Math.Round(decimal.ToDouble(dec), 3);

            Console.WriteLine($"Decimal: {dec}\nDouble: {d}");

            var parameters = new Dictionary<string, object>

            {

                {"price", d},

            };

            string body = JsonConvert.SerializeObject(parameters, Formatting.Indented);

            Console.WriteLine($"JSON: \n{body}");

            var deserialized = (Dictionary<string, object>)System.Text.Json.JsonSerializer.Deserialize(body, typeof(Dictionary<string, object>));

            var element = (JsonElement)deserialized["price"];

            double deserializedDouble = element.GetDouble();

            Console.WriteLine($"deserialized double: {deserializedDouble}");

            parameters["price"] = deserializedDouble;

            string serialized = System.Text.Json.JsonSerializer.Serialize(parameters, new JsonSerializerOptions

            {

                WriteIndented = true

            });

            Console.WriteLine($"Reserialized JSON: \n{serialized}");

        }

    }

}

​