Cherche la silver-rimmed spectacles.
I just got hold of a copy of a book I haven't seen in over forty years: "The Trachtnberg Speed System of Basic Mathematics". Part of the Foreword has me stumped:
"... A small girl with beribboned braids was asked to find the solution of 735352314 times 11. She came up with the correct answer --- 8088875454 --- in less time than you can say multiplication table. A thin, studious-looking boy wearing silver-rimmed spectacles was told to multiply 5132437201 times 452736502785. He blitzed through the problem, computing the answer --- 2323641669144374104785 --- in seventy seconds."
I know how to do the former trick (the multiplying-by-eleven trick is well known), but I'm baffled by the latter feat. Do any of you have any insights?
Jim