Excel numeric precision is 15 significant digits.
If you don't need to calculate with the number, for example credit card
numbers, make it text by preceding the entry with an apostrophe. The
apostrophe will not show.
Another way is to format the cells as text before entering the numbers.

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Kind Regards,

Niek Otten

Microsoft MVP - Excel

"Ravi Mohan Sahay" <Ravi Mohan wrote in
message ...
When I key in beyong 15 digits number in a cell of Excel 2000 or office XP
Excel eats up 16th digit and places a 0 and go-on like that.

Please help me