V5

V5 or V-5 may be:

• V5C (formerly V5), a United Kingdom vehicle registration document, being replaced by the EU-compatible vehicle registration certificate
• V5 engine, a V engine configuration with five cylinders
• V5 interface, a set of protocols defined by ETSI, including V5.1 and V5.2 in telecommunications
• V-5, a US Volunteer Naval Reserve classification for the Aviation Cadet program
• BMW V5, a platform number for the BMW Progressive Activity Sedan
• Chery V5, a 2006 Chinese Chery Automobile minivan model
• Hanlin eReader V5, an ebook reader
• Visual cortex Area V5 (visual area MT)
• The International Telecommunications Union callsign prefix for Namibia
• Royal Aruban Airlines IATA airline designator
• CATIA V5, a commercial CAD system

The square root of 5 is the positive real number that, when multiplied by itself, gives the prime number 5. It is more precisely called the principal square root of 5, to distinguish it from the negative number with the same property. This number appears in the fractional expression for the golden ratio. It can be denoted in surd form as: