Today's numbers, also called Hindu-Arabic numbers,
are a combination of just 10 symbols or digits:
1, 2, 3, 4, 5, 6, 7, 8, 9, and 0. These digits were
introduced in Europe within the XII century by
Leonardo Pisano (aka Fibonacci), an Italian mathematician.
L. Pisano was educated in North Africa, where he
learned and later carried to Italy the now popular
Hindu-Arabic numerals.
Hindu numeral system is a pure place-value system,
that is why you need a zero. Only the Hindus, within
the context of Ind-European civilizations, have
consistently used a zero. The Arabs, however,
played an essential part in the dissemination of
this numeral system.
Numerals, a time travel from India to Europe
The discovery of zero and the place-value system
were inventions unique to the Indian civilization.
As the Brahmi notation of the first 9 whole numbers...
Before adopting the Hindu-Arabic numeral system,
people used the Roman figures instead, which actually
are a legacy of the Etruscan period. The Roman
numeration is based on a biquinary (5) system.
To write numbers the Romans used an additive
system: V + I + I = VII (7) or C + X + X + I (121),
and also a substractive system: IX (I before X = 9),
XCIV (X before C = 90 and I before V = 4, 90 + 4 = 94).
Latin numerals were used for reckoning until late XVI century!
The graphical origin of the Roman numbers
Other original systems of numeration
Other original systems of numeration were being
used in the past. The "Notae Elegantissimae" shown
below allow to write numbers from 1 to 9999.
They are useful as a mnemotechnic aid, e.g.
the symbol K may mean 1414 (the first 4 figures of the square root of 2).
Chinese and Japanese contributions
The Ba-Gua (pron. pah-kwah) trigrams and the
Genji-Koh patterns, antique Chinese and Japanese
symbols, are strangely enough related to mathematics
and electronics. If all the entire lines of the trigrams
(___) are replaced with the digit 1 and the broken
lines (_ _) with the digit 0, each Ba Gua trigram
will represent then a binary number from 0 to 7,
and each number is laid in front of its complementary (0<>7, 1<>6, 2<>5, etc...).
Write "a", "b", "c", "d" and "e" under the five small
red sticks of each Genji-Koh pattern. By doing so,
you will have the 52 manners to CONNECT 5 variables
in boolean algebraics. The binded sticks form a
"conjunction" (AND, .), and the isolated sticks or
groups of sticks form a "disjunction" (OR, +).
The pattern at the top left represents: [("a" and "d")
or ("b" and "e") or "c"]
