In mathematics, the "Strong Law of Small Numbers" is the humorous title of a popular paper by mathematician Richard K. Guy and also the so-called law that proclaims:
"There aren't enough small numbers to meet the many demands made of them."
In other words, any given small number appears in far more contexts than may seem reasonable, leading to many apparently surprising coincidences in mathematics, simply because small numbers appear so often and yet are so few. Guy's paper gives 35 examples in support of this thesis. This can lead inexperienced mathematicians to conclude that these concepts are related, when in fact they are not.
Guy's observation has since become part of mathematical folklore, and is commonly referenced by other authors.
Second Strong Law of Small Numbers
The original strong law of small numbers was quickly followed by the second strong law of small numbers:
"When two numbers look equal, it ain't necessarily so!"
The second strong law of small numbers emphasizes the fact that two arithmetic functions taking equal values at small arguments do not necessarily coincide.