31 AUGUST 1996, Page 21

Shifting sands

Sir: Andrew Robson claims (Bridge, 17 August) that the odds against being dealt

13 spades exceed the world's grains of sand. The odds against the first card being a spade are plainly 13/52, of the second 12/51 and so on down to 1/40. The combined

odds are therefore 13 x 12 x . x 2 x 1 in 52 x 51 x . x 41 x 40; which is 1 in approximately 6.35 x 1011.

Sand grains vary in width from about Viso up to 1/25 of an inch, so an average cubic inch would contain some 125,000 grains.

With this data I reckon roughly 110 square yards of sand, 3 ft deep, would con- tain 6.35 x 1011 grains, but your readers may care to check my arithmetic.

D.KD. Foster

Beech House, Shifnal, Shropshire