XL has a specification limit of 15 decimal digits of precision (see
Help, "Specifications"). There's nothing you can to in XL itself to
extend the precision. There are a few add-ins around that you can Google
that claim to give up to 200 decimal digits of precision, but I haven't
tried any of them.

In article ,
"noel" wrote:

I seem to have hit a limit of 16 significant digits. For example:
1E+15 + 1 = 1000000000000001 (16 significant digits)
(note that 1000000000000000 is displayed but the 1's place value is still
retained)
whereas
1E+16 + 1 = 10000000000000000.
The loss of significant digits can be verified by resubtracting the the
initial large number, e.i.:
1E+15 + 1 - 1+E15 = 1, whereas
1E+16 + 1 - 1+E16 = 0.
Is there a way of getting past this limitation? I need more than 40
significant digits for some rather special calculations. I have created a
workaround which cuts numbers into up to 3 15-significant-digit pieces, but
it's inelegant and requires very long formulas. Thanks.