The calculated distance (air line) between Carrickmacross and An Muileann gCearr is approximately 40 miles respectively 64 kilometers.
By car or train, the actual journey to An Muileann gCearr is certainly longer, as only the direct route (as the crow flies) between Carrickmacross and An Muileann gCearr has been calculated here.
Air line (approximately)
64 kilometers
35 nautical miles