Year 1900 problem
Encyclopedia
The year 1900 problem concerns the misinterpretation of years recorded by only their last two digits, and whether they occurred before or after the year 1900. Unlike the year 2000 problem
, it is not tied to computer software
alone, since the problem existed before electronic computers did and has also cropped up in manual systems.
The most common issue raised by the year 1900 problem regards people's ages. Often, a person's birth year was registered with only two digits, on the assumption that either it was not important exactly how old a person is, or that no one lives longer than one hundred years. In several countries, especially in Europe, a national identification number
was introduced (often in the 1950s), including two-digit information about the birth year.
The largest unwelcome side effect from this is people 100 or more years old being mistaken for young children or in some cases, young children being mistaken for adults.
When handling the year 2000 problem, measures were sometimes taken to avoid or rectify this: modifying the national identification number, for instance.
number to store dates and times. The number 1.0 represents January 1, 1900 (or, in Excel for Mac, January 1, 1904). Numbers smaller than this display as a
In addition, Excel incorrectly regards 1900 as a leap year
and allows February 29 to be entered as a date in this year. This is for compatibility with Lotus 1-2-3
which also had this bug.
Year 2000 problem
The Year 2000 problem was a problem for both digital and non-digital documentation and data storage situations which resulted from the practice of abbreviating a four-digit year to two digits.In computer programs, the practice of representing the year with two...
, it is not tied to computer software
Computer software
Computer software, or just software, is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it....
alone, since the problem existed before electronic computers did and has also cropped up in manual systems.
The most common issue raised by the year 1900 problem regards people's ages. Often, a person's birth year was registered with only two digits, on the assumption that either it was not important exactly how old a person is, or that no one lives longer than one hundred years. In several countries, especially in Europe, a national identification number
National identification number
A national identification number, national identity number, or national insurance number is used by the governments of many countries as a means of tracking their citizens, permanent residents, and temporary residents for the purposes of work, taxation, government benefits, health care, and other...
was introduced (often in the 1950s), including two-digit information about the birth year.
The largest unwelcome side effect from this is people 100 or more years old being mistaken for young children or in some cases, young children being mistaken for adults.
When handling the year 2000 problem, measures were sometimes taken to avoid or rectify this: modifying the national identification number, for instance.
Microsoft Excel
Microsoft Excel cannot display dates before the year 1900, although this is not due to a two-digit integer being used to represent the year. Excel uses a floating pointFloating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
number to store dates and times. The number 1.0 represents January 1, 1900 (or, in Excel for Mac, January 1, 1904). Numbers smaller than this display as a
#VALUE! error.In addition, Excel incorrectly regards 1900 as a leap year
Leap year
A leap year is a year containing one extra day in order to keep the calendar year synchronized with the astronomical or seasonal year...
and allows February 29 to be entered as a date in this year. This is for compatibility with Lotus 1-2-3
Lotus 1-2-3
Lotus 1-2-3 is a spreadsheet program from Lotus Software . It was the IBM PC's first "killer application"; its huge popularity in the mid-1980s contributed significantly to the success of the IBM PC in the corporate environment.-Beginnings:...
which also had this bug.