In general, the percentage of food eaten can be a good number to use because:

1. It provides a standardized measure: Percentages allow for comparisons between different subjects, groups, or time periods, regardless of the total amount of food provided.
2. It indicates food intake: The percentage of food eaten can help determine if an individual or group is consuming an adequate amount of food or if there are issues with food intake.
3. It can be used to assess preference: In some cases, the percentage of food eaten can indicate a preference for certain types of food over others.
4. It can help monitor health and behavior: Changes in the percentage of food eaten can be an indicator of underlying health issues or behavioral changes in animals or humans.