Is 2 + 2 = 4 Really True? Around A.D.

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Is 2 + 2 = 4 really true?

Around A.D. 1200 Leonardo of Pisa (Fibonacci) discovered that a few weeks
after putting 2 male rabbits plus 2 female rabbits in the same cage, he
ended up with considerably more than 4 rabbits. Fearing that too strong a
challenge to the value 4 given in Euclid would meet with opposition,
Leonardo conservatively stated, "2 + 2 is more like 5 than 4" Even this
cautious rendition of his data was roundly condemned and earned Leonardo
the nickname "Blockhead." By the way, his practice of underestimating the
number of rabbits persisted; his celebrated model of rabbit populations
had each birth consisting of only two babies, a gross underestimate if
ever there was one.

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