English: Representation of Geometrical Magnitude by Number. The cardinal stage. The ordinal numbers represented by the ordinary numerals 1, 2, 3, ... and cardinal numbers by the Roman I, II, III, ... showing how the I, II, III, ... denote the successively larger groups of objects.
(Illustration from Encyclopædia Britannica Eleventh Edition, 1911, article Arithmetic)
This image comes from the 13th edition of the Encyclopædia Britannica or earlier. The copyrights for that book have expired in the United States because the book was first published in the US with the publication occurring before January 1, 1929. As such, this image is in the public domain in the United States.
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