It's a short story about the "Monte Carlo project" to randomly generate viruses. A pertinent quote:
The theory also included the best containment facilites in the world, and five hundred and twenty people all sticking scrupulously to official procedure, day after day, month after month, without a moment of carelessness, laziness or forgetfulness. Apparently, nobody bothered to compute the probability of that.
Especially his "Cabinet of mathematical curiosities".
"The music of the primes", by Marcus de Sautoy, is also worth reading.
If in any problem you find yourself doing an immense amount of work, the answer can be obtained by simple inspection.