# Multiplication of Fractionsby Isai Damier, Android Engineer @ Google

```/***************************************************************************
*  Author: Isai Damier
* Title: Multiplication of Fractions
* Project: geekviewpoint
* Package: algorithms
*
* Statement:
*   Multiplication the two given fractions
*
* Sample Input: {-5,6}, {6,8})
* Sample Output: {-5,8}
*
* Technical Details:
*   This is the same algorithm you learned in grade school:
*   1) multiply the numerators
*   2) multiply the denominators
*   4) reduce the resulting fraction using the GCD (greatest common
*     divisor) of its numerator and denominator.
*
**************************************************************************/
public int[] fractionMultiplication(int[] a, int[] b) {
int numerator = a[0] * b[0];
int denominator = a[1] * b[1];
int num = 0 > numerator? -numerator:numerator;
int den = 0 > denominator? -denominator:denominator;
int gcd = GCD(num, den);
gcd = 0 > gcd ? -gcd : gcd;
return new int[]{numerator / gcd, denominator / gcd};
}```
```import org.junit.Test;
import static org.junit.Assert.*;

public class NumbersTest {

/**
* Test of fractionMultiplication method, of class Numbers.
*/
@Test
public void testFractionMultiplication() {
System.out.println("fractionMultiplication");
Numbers numbers = new Numbers();
int[] expResult = {16, 15};
int[] result = numbers.fractionMultiplication(
new int[]{8, 5}, new int[]{10, 15});
assertArrayEquals(expResult, result);

expResult = new int[]{-5, 8};
result = numbers.fractionMultiplication(
new int[]{-5, 6}, new int[]{6, 8});
assertArrayEquals(expResult, result);
}
}```