  The intriguing law of anomalous numbers, also named Benford's law, states
that the significant digits of data follow a logarithmic distribution favoring
the smallest values. In this work, we test the compliance with this law of the
atomic databases developed at the National Institute of Standards and
Technology (NIST) focusing on line energies, oscillator strengths, Einstein
coefficients and radiative opacities. The considered databases are the Atomic
Spectra Database (ASD) and the NIST-LANL (Los Alamos National Laboratory)
Lanthanide/Actinide Opacity Database. The present study is not limited to the
first digit and the case of multipole lines is also considered. The fact that
the law is verified with a high accuracy means that the occurrence of digits
reflects the constraints induced, in a given angular-momentum coupling, by the
selection rules for atomic processes. As a consequence, Benford's law may be of
great interest to detect inconsistencies in atomic databases.
