If you really need to record more than 15 digits (eg for a credit card
number, or some account numbers), then you must enter these as text,
either by pre-formatting the cell as text or by typing an apostrophe
before the number when you enter it - the apostrophe will not show in
the cell, but it is visible in the formula bar.

As these are text values, you will not be able to do any normal
arithmetic on them, but then, who wants to take 10 percent (say) of a
credit card number?

Hope this helps.

Pete

LisaS wrote:
When entering numbers with more than 15 digits all the digits after the 15th
place automatically change to zeros.

It doesn't matter what the colum width is, the cell format is number, 0
decimal, no commas. If I change the format to text all the digits hold as
entered. Why don't they hold as entered when formated as numbers

example: I enter 1231231234567123456 the number changes
to 1231231234567120000