I would suggest that you count the digits again.
A quote from MS Article
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Microsoft Excel retains 15 significant digits. To display all 15 digits, you
must use a number format (custom or built-in) other than General. The General
number format displays up to 11 numeric characters, with the decimal point
counting as a numeric character. Therefore, if the number contains a decimal
point, Excel can display up to 10 significant digits, but if the number does
not contain a decimal point, Excel can display up to 11 significant digits
Adding more numbers to the left of the decimal point causes the number to
appear in exponential notation.