How can I aggregate and group these texts by; 307, 308 and 310.
I have hundreds of text which range from 0-350. So a way to aggregate them just based of the first 3 digits.
You can use Aggregate with the group by expression left ("input",3), where input is the name of the field containing the numbers.
Demonstrated here with Categorized layer styling: all points get catagorized in different colors based on the first three numbers: