A version of this puzzle originally appeared in the October 1960 issue of Scientific American.

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Join Mrs. Gray for a Mystery Math Mistake with D.C. He needs your help with his number bonds. We will be counting pictures with ten and some more to answer the question "how many?" Episode ...

The idea of an animal that can count or do math might sound like something out of a viral news story or TikTok video. But a sense of quantity, sometimes called "numerosity," appears across a ...

Students in Melissa Williams' kindergarten class at the Westminster School in Atlanta, Georgia, practice connecting quantities to written numbers — a key part of number sense. Credit: Holly Korbey for ...