The national highway from Delhi to Calcutta via Mathura and Varanasi is numbered

1. The question asks for the number of the National Highway connecting Delhi to Calcutta (Kolkata) via Mathura and Varanasi, according to the old numbering system prevalent in 1995. 2. Under the old numbering system, the highway connecting Delhi to Kolkata was National Highway 2 (NH 2). 3. This route indeed passed through major cities including Mathura, Agra, Kanpur, Allahabad (Prayagraj), Varanasi, and Asansol before reaching Calcutta. 4. Note: The National Highway numbering system has been rationalized since 2010, and this route is now part of NH 19 and NH 44.