Martin Gardner passed away last week on 22 May, aged 95. Wikipedia is a good place to read about his contribution in bringing mathematics to the public. My favourite article of Gardner’s is **Six Sensational Discoveries that Somehow or Another have Escaped Public Attention,** Sci. Amer. **232**, 127-131, Apr. 1975. (Also published in Time Travel and Other Mathematical Bewilderments.) Inside, Gardner announces six discoveries among which a counter-example to the four colour theorem. Before you jump off your seat, the article was dated 1st April 1975. Yes, it’s another very clever hoax.

The best among the six is the claim that

[tex] e^{\pi \sqrt{163}} = 262537412640768743.99999999999925 [/tex]

is exactly an integer and this fact was found by Ramanujan. The attribution to Ramanujan was clever not because of Ramanujan’s remarkable prowess of calculation but that constant is actually an evaluation of the modular j-invariant

[tex]j(\tau) = q^{-1} + 744 + 196884q + 21493760q^2 + \ldots[/tex]

and of course [tex]Q(\sqrt{-163})[/tex] has class number one.

Another interesting wrinkle is that the supercomputers in use at the time were CDC 6000 and 7000 series mainframes capable of double-precision floating-point hardware operations with 29 decimal digits precision.

This April Fools joke challenged a couple of our ace programmers at the University of Minnesota Computer Center with that April, 1975 issue. They of course, were stymied to find out with a simple program whether Gardner was correct because insidiously, the fractional part contains 9′s from digits 19 through 30!

So one of these ace programmers, Kevin Mathews, wrote his own multiple-precision arithmetic routines in software which computed in excess of 50 significant digits and discovered the hoax!