The Pi Approximation Day is celebrated on July 22 as the date 22/7 marks the approximate value of Pi (22.7). However, Pi day is celebrated on March 14, as the date marks the actual value of Pi - 3.14.

Mathematics of Computation, Vol. 34, No. 150 (Apr., 1980), pp. 441-463 (23 pages) Constructive proofs and several generalizations of approximation results of J. H. Bramble and S. R. Hilbert are ...

S. Das, H. Dutta, Degree of approximation of signals in certain Lipschitz classes by the Zweier–Euler product summability method of Fourier series, Math. Methods ...