A photon-number-resolving detector with single-photon resolution is described and demonstrated. It has $10\phantom{\rule{0.3em}{0ex}}\mathrm{bits}$ of resolution, does not require cryogenic cooling, and is sensitive to near ir wavelengths. This performance is achieved by flood illuminating a $32\ifmmode\times\else\texttimes\fi{}32$ element ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{AsP}$ Geiger-mode avalanche photodiode array that has an integrated counter and digital readout circuit behind each pixel.