Excel does not allow more than 15 digits

I noticed today that Excel does not allow more than 15 digits in a cell. If you a type a number with more than 15 digits into an excel cell, the digits after the first 15 get replaced by zeroes. I had a hard time trying to figure out how to fix this. You can make the cell accept more than 15 digits by:
[1] pre-formatting the cells as text fields BEFORE pasting the values
or
[2] by start the number with an apostrophe i.e. '

From Microsoft Knowledge Base 269370:

"CAUSE
Excel follows the IEEE 754 specification on how to store and calculate floating-point numbers. Excel therefore stores only 15 significant digits in a number, and changes digits after the fifteenth place to zeroes.

WORKAROUND
To work around this behavior, format the cell as text. The cell can then display up to 1,024 characters."

Related Links:
- http://support.microsoft.com/kb/269370
- http://www.mrexcel.com/archive/Formatting/20648.html