From the history of maths
Georg Cantor
He showed that some infinities are bigger than others: there are more real numbers than whole numbers.
His diagonal argument (1891) is still the classic way to prove it.
Unknown author, Public domain, via Wikimedia Commons
Where you’ll meet Cantor here
LogicCounting
They turn up beside problems and lessons on these topics.
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Shakuntala Devi
Known as the “human computer”, in 1980 at Imperial College London she multiplied two 13-digit numbers in her head in 28 seconds.
She also wrote popular books of puzzles and mental arithmetic.
Central News Agency (Taiwan), Public domain, via Wikimedia Commons