In 1971, Nicaragua issued a set of ten stamps featuring *The ten mathematical formulas that changed the face of the earth*. These were:

1 + 1 = 2, the Pythagorean law for right-angled triangles, Archimedes’ law of moments, Napier’s law of logarithms, Newton’s law of gravitation, Maxwell’s law of electromagnetism, de Broglie’s law of light waves, Tsiolkovskii’s law of rocket motion, Boltzmann’s law of entropy, and Einstein’s law of relativity.

On the back of each stamp is some explanation of the formula shown.

*[Nicaragua 1971]*