Cell should not allow user to type more than 3 decimal values

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This is good, but it’s not gonna meet my requirement, will explain my requirement completely, please share an example that gonna meet my requirement.

My requirement is: In the cell it should not allow the user to type text and any symbols except dot(.), also the user should not type more than 3 decimal values and 5 whole number digits.

I guess, your example will not meet my requirement, so please provide me an example that will meet my complete requirement.

Thanks,
Bala