The number of primes less than 1,000,000,000 is 50,847,478 ...
            — G.H. Hardy, A Mathematician’s Apology, §14, page 23.

   )copy dfns pco

   ¯1 pco 1e9
50847534

Bertelsen’s number: an erroneous name erroneously given the erroneous value of  π(1e9) = 50847478.
            — MathWorld