Sifran

Since the 15th century, a symbol has been found in Spanish, Mexican, Peruvian, and other Hispanic manuscripts, which is an almost rounded “ U ” or an unfinished “ O ”. An oval can be completed and crossed out by one horizontal line - then the symbol becomes identical to the Greek letter " θ (theta) " - or even crosswise. In the latter case, it looks like zero with a cross inside it. There are options with both one and two, with both horizontal and vertical lines. The name of this symbol is “ calderon ” ( Spanish: calderón ), the purpose is to separate the digits when writing large numbers, first in Roman and then Arabic numbers, that is, for the visual separation of thousands from hundreds, tens and ones. In the XVIII century, calderon was used in prints in the form of the Greek letter " ϡ (sampi) " ^{[1] [2] [3]} .

The symbol is also found in sources written in the 15th century in northwestern Italy. Therefore, the American mathematician Florian Caggiori suggested that the calderon is the result of the centuries-old transformation of some of the varieties of Roman symbols used to write thousands: Ⅿ, ↀ, ⅭⅠↃ, ⅭⅠⅠↃ, ͳ ^{[4] [1]} .

In Portugal, a symbol with the same purpose, but with a different style, was called "sifran" ( port. Cifrão from lat. Cifra - number ). It is identical to the modern dollar symbol ($), but, according to Caggiori, has a different origin and goes back to some varieties of the Spanish calderon ^{[1] [2]} .

At the end of the XVIII century, continuing to fulfill the functions of a separator of digits, sifran was used to denote the face value of banknotes in Portuguese realities (see illustration on the right). For the first time, these banknotes were issued in 1797 ^[5] .

In the first half of the 19th century, sifran appears in the same quality on banknotes nominated in Brazilian realities (see the first illustration below). When writing, the symbol separated three zeros in the sum of money on the right, indicating, to the left of the sign, the amount in a multiple of units - milares . Sometimes it was used in combination with the abbreviated designation of real rs . So, the sum of 1000 reais (1 milleraise) was designated 1 $ 000 , Rs. 1 $ 000 or 1 $ 000 rs , and the sum of 1 000 000 reais (1000 miles) is 1: 000 $ 000 (millions were separated by a colon ; see the second illustration below) ^[3] . One of the recording options is without zeros, that is, $ 1 , which means “1 milleraise” (see the third illustration below).

At the beginning of the 20th century, with the introduction of escudos , which replaced the Portuguese real in the ratio of 1: 1000, the symbol began to function as a decimal separator , that is, to separate the main currency (escudo) and its fractional ( centavo ), equal to ¹ ⁄ _{100 of the} main. 2 $ 50 means “two escudos and 50 centavos” (see the fourth illustration below), and $ 60 means “ 60 centavos” (see the fifth illustration below) ^[6] .

According to one version, being an older sign, Sifran became the prototype of the dollar symbol ^{[7] [8] [9]} .

As a separator of digits and a decimal separator, sifran is not included in the Unicode standard. Performing the functions of a brief presentation of escudos, millerais, real and other currency units of Portuguese-speaking countries, it is considered as a sign identical to the dollar symbol, or a local version of the dollar symbol ^{[10] [11] [12] [13]} .

List of major monetary units in Portuguese-speaking countries

• A History of Mathematical Notations / by Florian Cajori. - Vol. I. - New York: Cosimo, 2007 .-- ISBN 978-1-60206-685-4 .
• A History of Mathematical Notations / by Florian Cajori. - Vol. II. - New York: Cosimo, 2007 .-- ISBN 978-1-60206-714-1 .
• History of Mathematics / by David Eugene Smith. - Vol. I. - 1953. - ISBN 0-486-20430-8 .
• Standard Catalog of World Paper Money General Issues (1368-1960) / by George S. Cuhaj. - Krause, 2010 .-- ISBN 978-1-4402-1293-2 .