The verse 'gopi bhagya' basically follows Katapayadi system[0]. Earliest known usage of Katapayadi system was in 683 AD. That verse is from a 1965 book called "Vedic Mathematics" by Bharati Krishna Tirtha Maharaja[1].
The Quora blog you linked has issues with terminologies and timelines of this specific "Vedic Mathematics" book - such as calling these mental calculation techniques and tricks as Vedic even though there are no references to them in Vedas[2]. This is more of a political matter ;) And, it's already pointed out in the article linked by OP[3]. I'm quoting it here:
It must be pointed out that these sutras given by Tirtha Maharaja are created by the author himself, as stated in the introduction to his book, "Vedic Mathematics" (published posthumously) and are therefore not actually Vedic.
These mathematical sutras are Vedic only in the sense that they are inspired by the Vedas in the mind of one dedicated to the Vedas. Thus the title "Vedic Mathematics" is not correct.
The Quora blog you linked has issues with terminologies and timelines of this specific "Vedic Mathematics" book - such as calling these mental calculation techniques and tricks as Vedic even though there are no references to them in Vedas[2]. This is more of a political matter ;) And, it's already pointed out in the article linked by OP[3]. I'm quoting it here:
It must be pointed out that these sutras given by Tirtha Maharaja are created by the author himself, as stated in the introduction to his book, "Vedic Mathematics" (published posthumously) and are therefore not actually Vedic.
These mathematical sutras are Vedic only in the sense that they are inspired by the Vedas in the mind of one dedicated to the Vedas. Thus the title "Vedic Mathematics" is not correct.
[0]http://en.wikipedia.org/wiki/Katapayadi_system
[1]http://en.wikipedia.org/wiki/Vedic_Mathematics_%28book%29
[2]http://en.wikipedia.org/wiki/Bharati_Krishna_Tirthaji#Mathem...
[3]http://www.vedicsciences.net/articles/vedic-mathematics.html