Lewis & Short

nŭmĕrābĭlis, e, adj. [numerus], that can be numbered or counted, numerable (poet. and very rare): calculus, Ov. M. 5, 588: populus utpote parvus, easily numbered, Hor. A. P. 206.
Hence, nŭmĕrābĭlĭ-ter, adv., Ps.-Aug. Spec. 20.