The X-Number structured number-entry
procedure is based in the usage of Verbal
Numerals. A verbal numeral is the representation of a
number by using a sequence of digits and structures. In the decimal
system, numbers are actually combinations of digits and numerical
structures, where numerical structures are the main multiples of ten
that had been assigned a single word in a given language. Most of
the modern languages have a word to represent these
structures. In English, for example, the 100 structure is called
"Hundred," the 1,000 structure is called "Thousand,"
and the 1,000,000 structure is called "Million." In
Japanese and other Asian languages, 10,000 is a numerical structure.
If a symbol is used to
represent a numerical structure, then a number can be represented by a sequence
of numbers and numerical structures arranged in the same way as the number is
pronounced verbally. This is called a Verbal Numeral. Lets
say for example, that we use the symbols "H", "T",
and "M" to represent the structures "Hundred,"
"Thousand," and "Million." Then numbers can be
represented as shown in the following examples:
Notice that, in most of the
cases, the number of symbols required to represent a number is smaller
when the Verbal Numeral representation is used.
US Patent 5,623,433
describes the concept of the Verbal Numerals and covers the algorithms
used to convert Verbal Numerals into Decimal Numerals and vice-versa.
using the concept of the Verbal Numerals, it is possible to design a 13-key numerical keyboard
that allows entering a number in a way similar
to its verbal expression.
In the following examples, [H] represents
the hundred or 00 key, [T] is the thousand or 000 key, and [M]
is the million or 6x0 key.
For example, to enter the number "Two million forty seven"
you may enter the sequence [M].
you can still enter it as  which is the traditional procedure, but
the structured entry mode is more natural and requires less number of
Discover why "One
thousand one hundred" [T][H] is different from "One hundred thousand"
The structure keys can also be represented
as: , , and [6x0], which stand
for Hundred, Thousand and Million
(to make them language independent).
Because of this verbal approach, the user
does not have to convert mentally the number into a sequence of digits prior to typing it
into the keyboard.
Another advantage of using a
13-key design is that it reduces the average number of keystrokes required to enter a
number when the number contain zeroes. Note that in the first example provided above, to enter the number
2000047, the 13-key design required only 4 keystrokes against the 7 required by a 10-key
design. This holds true for most large numbers. This advantage is language
independent and can be useful even in non-western languages such as Japanese and Chinese.
Finally, note that the X-Number method is an
extension, not a replacement, to the functionality of the regular ten-key design.
Users can still use the traditional digit-by-digit method. A 13-key
device allows mixing both methods during the same number-entry operation.