In this tutorial, we will learn to write a program in c to convert a decimal number into a binary number. Here we will use the division concept to convert it into a binary number.

Before moving towards the writing program let’s know about the binary numbers.

## What is the Binary Number?

A **binary number** is a number that is expressed in the **base-2 numeral system**. This expression contains only numbers 0 and 1.

For eg:

If we want to write decimal in binary

1 can be written as 0 0 0 1 = 2^0

2 can be written as 0 0 1 0 = 2^1

3 can be written as 0 0 1 1 = 2^1 + 2^0

4 can be written as 0 1 0 0 = 2^2

## How our binary number conversion program will behave?

- Binary number conversion program in C will take decimal as an input.
- We will divide the number by 2 to find the remainder and store that remainder.
- After storing reminder replace the original number with the new number which we got after divided by two.
- This process will continue till original number become 0.
- Here remaindar is binary number which we will get everytime.

## C Program to convert decimal number into binary

```
#include <stdio.h>
int main()
{
int arr[10], num, i, j;
printf("Program to Convert Decimal Number into Binary\n");
printf("Please Give a Number to Convert in Binary: ");
scanf("%d", &num);
printf("Binary Number of %d is = ",num);
for(i = 0; num > 0; i++)
{
arr[i] = num % 2;
num = num / 2;
}
for(j = i - 1; j >= 0; j--) {
printf(" %d ", arr[j]);
}
printf("\n");
return 0;
}
```

**Output**

```
Program to Convert Decimal Number into Binary
Please Give a Number to Convert in Binary: 23
Binary Number of 23 is = 1 0 1 1 1
```

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