Convert Decimal to Roman in Java

Converting Decimal to Roman, such as the example 3120 = MMMCXX

Algorithms Used:
1. If multiples of 1000 replaced by the M
2. If the rest above 900 added CM
3. If the rest above 500 added D
4. If the rest above 400 added CD
5. If the rest multiples of 100 replaced with C //repeat multiplication algorithm of 1000
6. If the rest above 90 added XC
7. If the rest above 50 added L
8. If the rest above 40 added CL
9. If the rest multiples of 10 replaced with C //repeat multiplication algorithm of 1000 or 100
10. If the rest above 9 added IX
11. If the rest above 5 added V
12. If the rest above 4 added IV
13. The rest added I

For the above 1000 repeat multiplication algorithm of 1000 by find the number in Roman symbol

Implementation in Java Code:
In this coding it's used If Else If
Create a class with the name Conversion

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package inymgd;

/**
 *
 * @author monday
 */

import java.io.*;

public class Conversion {
    
    public static void main (String args[]) {
        try{            
            //variable declaration for number
            int number;            
            do{
                //show input stream
                System.out.print ("input decimal number (1-4000): ");

                //read input stream and add the value to number
                BufferedReader bfr = new BufferedReader (new InputStreamReader(System.in));
                number = Integer.parseInt(bfr.readLine());
            }while(number < 1 || number > 4000);

            //variable declaration for roman
            String roman = "";
            //algorithm implementation
            do{
                if (number >= 1000){
                    number = number - 1000;
                    roman = roman + "M";
                }
                else if (number >= 900){
                    number = number - 900;
                    roman = roman + "CM";
                }
                else if (number >= 500){
                    number = number - 500;
                    roman = roman + "D";
                }
                else if (number >= 400){
                    number = number - 400;
                    roman = roman + "CD";
                }
                else if (number >=100){
                    number = number - 100;
                    roman = roman + "C";
                }
                else if (number >=90){
                    number = number - 90;
                    roman = roman + "XC";
                }
                else if (number >=50){
                    number = number - 50;
                    roman = roman + "L";
                }
                else if (number >=40){
                    number = number - 40;
                    roman = roman + "XL";
                }
                else if (number >=10){
                    number = number - 10;
                    roman = roman + "X";
                }
                else if (number >=9){
                    number = number - 9;
                    roman = roman + "IX";
                }
                else if (number >=5){
                    number = number - 5;
                    roman = roman + "V";
                }
                else if (number >=4){
                    number = number - 4;
                    roman = roman + "IV";
                }
                else if (number >=1){
                    number = number - 1;
                    roman = roman + "I";
                }
            }while (number > 0);

            //show the result of conversion
            System.out.println("roman symbol: "+ roman);
            
        }catch (IOException io){
            System.out.println ("Error: " + io.getMessage());
        }
    }
}