QGIS: Change String to Number values in the shapefile

In QGIS, you can convert a string to a number using the "Field Calculator" tool. First, open the attribute table for the layer you wish to modify. Next, click the "Open Field Calculator" button. In the "Expression" box, type "to_real(" followed by the name of the field containing the string you want to convert, and closing parenthesis. For example, to convert a string field named "string_field" to a numeric field, input "to_real("string_field")" in the Expression box. You can also modify the output field name and data type by selecting the appropriate options. Finally, click "OK" to complete the conversion. The original string field will remain in the attribute table, while the new numeric field will be added to the table.

1. Open "Properties"

2. Go to "Field Calculator"

3. Check "Update Existing field"

4. to_real("attributeName")

5. Save edits

6. Repeat the same for each attribute