> In Java, the **`BigInteger` class** handles big integer mathematical operations that are outside the limits of all primitive types.

The **`mod` method** of the `BigInteger` class can be used to find the `remainder`(modulo) of the division of the current `BigInteger` object by the passed `BigInteger`.

#   
#  Syntax

```java
public BigInteger mod(BigInteger val)
```

#   
#  Parameters
This method takes a `BigInteger` object as an argument. This method throws `ArithmeticException` if the value of the argument is less than or equal to `0`.

##  
## Return value 

This method returns a `BigInteger` object. The value of the returned BigInteger object is the remainder of the division of the current `BigInteger` value by the passed argument value. 

The return value will be a positive `BigInteger`.

> Both the `mod` and `remainder` functions can be used to get the remainder, but the `mod` function always returns a positive `BigInteger`.

##  
## Code

The example below demonstrates how to use the `mod` method.

import java.math.BigInteger;

class BigIntegerModExample {
    public static void main( String args[] ) {
        BigInteger val1 = new BigInteger("-13");
        BigInteger val2 = new BigInteger("2");
        BigInteger result = val1.mod(val2);
        System.out.println(result);
    }
}

#   
## Explanation 

In the code above:

* In line 1, we import the `BigInteger` class.
```
import java.math.BigInteger;
```

* In lines 5 and 6, we create two `BigInteger` 
 objects, `val1` with value `-13` and `val2` with value `2`. 

```
BigInteger val1 = new BigInteger("-13");
BigInteger val2 = new BigInteger("2");
```
* In line 7, we call the `mod` method on the `val1` object with `val2` as an argument. This method call will return a `BigInteger` that has a value equal to the remainder of `val1 / val2` (i.e. -13 % 2 = -1). 

  The `mod` function always returns a positive value, so the result will be `1`, not `-1`. 

>If you need the negative value, you can use the `remainder` method. 

```
BigInteger result = val1.mod(val2); //1
```

What is the BigInteger.mod method in Java?

BigInteger's `mod` method computes the division remainder and returns it as a positive BigInteger.