Why can the data type number field store more decimal places than defined in the CRM Survey?
The user answers a question of type number. The user enters a decimal number in the question responses field. Example: 2.8.
After saving or submitting the survey question, the field shows the number rounded-off to the nearest integer. Example: 3. The value is stored as 2.8 in the database.
This is working as designed. Salesforce® allows the custom field to save records with decimal places. It changes the display to match the definition, but they are stored in the database as inserted.
Salesforce Help Documentation: Data type number field can store more decimal places than defined