The English mathematician Abraham de Moivre in old age once found that duration of sleep increases to 15 minutes a day. Having made an arithmetic progression, he set a date when it would reach 24 hours - November 27, 1754. On this day he died.
The authenticity of euro banknotes can be checked by its serial number, letter number and eleven digits. You need to replace the letter on its serial number in the English alphabet, add up this number
and the rest numbers, then put the result numbers, until you get one character. If this figure is 8, the note is authentic.
There is an opinion that Alfred Nobel did not include mathematics to the list of disciplines of his premium due to the fact that his wife cheated on him with a mathematician. In fact, Nobel was never married.The real reason for ignoring mathematics is unknown, but there are a few assumptions. For example, at that time Prize in Mathematics from the Swedish king was already existed. The other reason is that Mathematics do not make important inventions for mankind, because this science is purely theoretical.
Reuleaux triangle is a geometric figure formed by the intersection of the three circles of equal radius a centered at the vertices of an equilateral triangle with side a. The drill made on the basis of Reuleaux triangle, allows to drill square holes (with the inaccuracy of 2%).