You can specify a specific string or number as a default value, as long as the column holds a string or number data type.
You must ensure that the default specified can be converted to the data type of the column.
Default strings and numbers are useful when there is a typical entry for a given column. For example, if an organization has two offices, the headquarters in city_1 and a small office in city_2, you may want to set a default entry for a location column to city_1, to make data entry easier.