Calcutta, Aug. 13: A retired US pharmacist claims he has invented a method of mental multiplication that has been in use in India and abroad for years by practitioners of “Vedic mathematics”.

The Calcutta-based Vedic Maths Forum India has started a blog on its website to debunk the claim by Albert Clay, 75. It is talking to lawyers to see if it can get a US court to revoke the copyright Clay has obtained on his six-page booklet explaining the method.

The matter came to light after The News & Observer, a North Carolina-based newspaper, carried an interview of Clay, whose “How to Multiply Any Number by Any Number in Your Head” has been registered as TXu001325432 in the US Copyright Office.

“There may not be anybody else in the world who knows how to do this but me,” claims Clay in the interview published on August 10. The statement has been challenged on the daily’s site by readers familiar with Vedic mathematics.

The article describes Clay’s method by taking a pair of two-digit numbers and coming up with the answer.

“This is exactly what our ‘vertically and crosswise’ method of multiplication is,” said VMFI president Gaurav Tekriwal over the phone from South Africa.

In the interview, Clay claims he had worked out the system as a high school junior and had never shown it to anyone except a mathematics teacher who did not take it seriously.

“But the method can be found in Vedic Mathematics, a treatise published in 1965 by Swami Bharati Krishna Tirtha. Look up the chapter on multiplication and the method has been used in both arithmetical and algebraic operations more than once,” V.G. Unkalkar, author of Magical World of Mathematics: Vedic Mathematics, told The Telegraph from Bangalore.

Professor Amartya Dutta, a mathematician with the Indian Statistical Institute, Calcutta, said: “While the Vedic origin of ‘Vedic mathematics’ may be debated, there can be no doubt about the method used in Bharati Tirtha’s 1965 book.”

A copyright protects only the text or “form of expression” but not the subject matter — which means others can write their own original article on the subject. “US patent law does not allow patenting of ideas but there you can take a patent on the explanation of the idea,” Tekriwal said.

The Telegraph tried to contact Clay over email but got only an automated reply: “… I have listed how to obtain a copy of my math system below. If your (sic) requires a more personal response, I will try to respond as time allows. Thank you for your understanding.”