Math multiplyHigh() method in Java with Examples

The multiplyHigh(long x, long y) method of Math class is used to return the most significant 64 bits from the 128-bit product of two 64-bit factors. This method takes two long values as input and a long is a 64-bit number. This method multiplies both long values and returns the most significant 64 bits from the product result which can be 128 bit long.

Syntax:

public static long multiplyHigh(long x, long y)

Parameters: This method accepts two long x, y as parameter where x and y are argument we want to multiply.

Return Value: This method returns the most significant 64 bits long value from the 128-bit product of two 64-bit numbersi.e. X * Y.

Note: This method was added in JDK 9. Hence it wont run in Online IDE.

Below programs illustrate the multiplyHigh() method:

Program 1:

// Java program to demonstrate
// multiplyHigh() method of Math class

public class GFG {

    // Main method
    public static void main(String[] args)
    {

        // two long values
        long a = 45267356745l, b = 45676556735l;

        // apply multiplyHigh method
        long c = Math.multiplyHigh(a, b);

        // print result
        System.out.println(a + " * "
                           + b + " = "
                           + c);
    }
}

Output:

45267356745 * 45676556735 = 112

Program 2: Multiplying two long contains Long.MAX values.

// Java program to demonstrate
// multiplyHigh() method of Math class

public class GFG {

    // Main method
    public static void main(String[] args)
    {

        // two Integer values
        long a = Long.MAX_VALUE, b = Long.MAX_VALUE;

        // apply multiplyHigh method
        long c = Math.multiplyHigh(a, b);

        // print result
        System.out.println(a + " * "
                           + b + " = " + c);
    }
}

Output:

9223372036854775807 * 9223372036854775807 = 4611686018427387903

References: https://docs.oracle.com/javase/10/docs/api/java/lang/Math.html#multiplyHigh(long, long)