and one gram is approximately . Fine-structure constant The fine-structure constant is close to, and was once conjectured to be precisely equal to, . is a dimensionless physical constant, so this coincidence is not an artifact of the system of units being used. Planet Earth The radius of geostationary orbit, is within 0.02% of the variation of the distance of the moon in a month (the difference between its apogee and perigee), , and 5% error of the length of the equator, . See also Almost integer Anthropic principle Birthday problem Exceptional isomorphism Narcissistic number Sophomore's dream Strong law of small numbers Experimental mathematics Koide formula References External links В. Левшин. – Магистр рассеянных наук. – Москва, Детская Литература 1970, 256 с. Davis, Philip J. - Are There Coincidences in Mathematics - American Mathematical Monthly, vol. 84 no. 5, 1981. Hardy, G. H. – A Mathematician's Apology. – New York: Cambridge University Press, 1993, () Various mathematical coincidences in the "Science & Math" section of futilitycloset.com Press, W. H., Seemingly Remarkable Mathematical Coincidences Are Easy to Generate Mathematical terminology Recreational mathematics