Here is a Java program to convert decimal number to binary number. In this java program, we will take a decimal number as input from user and then convert it to binary number. Before jumping into java program, here is the brief introduction of binary and decimal number systems.

**Binary number**system is base 2 number system and uses 0 and 1 digits. For Example: 0, 1, 01, 101, 1101**Decimal number**system is a base 10 number system using digits for 0 to 9. For Example: 6, 3, 12, 10, 123

**Algorithm to convert decimal to binary number**

- Divide the input decimal number by 2 and store the remainder.
- Store the quotient back to the input number variable.
- Repeat this process till quotient becomes zero.
- Equivalent binary number will be the remainders in above process in reverse order.

Suppose input decimal number is 12

Step 1. 12/2 , Remainder = 0, Quotient = 6

Step 2. 6/2 , Remainder = 0, Quotient = 3

Step 3. 3/2 , Remainder = 1, Quotient = 1

Step 4. 1/2 , Remainder = 1, Quotient = 0

Now, the Binary equivalent of 12 is the remainders in reverse order : 1100

## Java Program to convert Decimal to Binary Number

package com.tcc.java.programs; import java.util.Scanner; public class DecimalToBinary { public static void main(String[] args) { long dec; Scanner scanner; scanner = new Scanner(System.in); System.out.println("Enter a Decimal Number"); dec = scanner.nextLong(); // Calling decimalToBinary method to convert decimal // number to binary System.out.println("Binary Number : " + decimalToBinary(dec)); } public static long decimalToBinary(long n) { long remainder, binary = 0, i = 1; while (n != 0) { remainder = n % 2; n = n / 2; binary = binary + (remainder * i); i = i * 10; } return binary; } }Output

Enter a Decimal Number 20 Binary Number : 10100

Enter a Decimal Number 16 Binary Number : 10000

**Recommended Posts**