Excel can only store up to 15 significant digits in a number. Anything beyond that will be turned into zeros. Do you really need this as a number? I don't even know the word for a number that large, and if you have such large numbers, surely the singles at the end are fairly insignificant, given the magnitude.
If, however, these numbers are not used in any calculations, you can simply precede them with a single quote, then Excel treats them as text and you can have a lot more that 15 digits.
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Mr_Ron (New Contributor)