The calculated distance (air line) between Ad Dīwānīyah and As Samawah is approximately 51 miles respectively 81 kilometers.
By car or train, the actual journey to As Samawah is certainly longer, as only the direct route (as the crow flies) between Ad Dīwānīyah and As Samawah has been calculated here.
Air line (approximately)
81 kilometers
44 nautical miles