It sounds like a 40Gb Drive, it is quite normal not to actually 'see' all 40Gb some of which is used by the System.
Hover the mouse cursor over the drive's icon in My Computer then tell us what you see - it should show Amount Used and Amount Free.
Samsung Galaxy A8 review: Hands-on
Illustrator Juan Esteban Rodriguez on creating highly detailed official film posters for Star Wars…
iMac Pro review
Comment savoir si quelqu'un a bloqué votre numéro de téléphone ?