@Test
    public void testInvalidSubstract() {
        LargePositiveInteger number1 = LargePositiveInteger.TWO; //2
        int[] bytes = {1,0,0,0};
        LargePositiveInteger number2 =  new LargePositiveInteger(bytes); //10
        Assert.assertEquals("16777214",number2.subtract(number1).toString());
    }