### Question:
UInt64 implements UInt<UInt64> { @Override public UInt64 multiply(UInt64 other) { return new UInt64(value * other.value); } UInt64(long value); @Override UInt64 add(UInt64 other); @Override UInt64 multiply(UInt64 other); @Override UInt64 subtract(UInt64 other); @Override UInt64 negateUInt(); @Override boolean isZero(); @Override int getBitLength(); @Override byte[] toByteArray(); @Override BigInteger toBigInteger(); @Override long toLong(); @Override int toInt(); @Override String toString();  }### Answer:
@Test public void multiply() { Assert.assertEquals(42 * 123, left.multiply(right).toInt()); }