This study does not mention whether the participants where asked to do the arithmetic in their head : https://johnjerrim.files.wordpress.com/2018/03/piaac_worki

This study does not mention whether the participants where asked to do the arithmetic in their head : https://johnjerrim.files.wordpress.com/2018/03/piaac_working_report_march_2018.docx https://johnjerrim.files.wordpress.com/2018/03/piaac_working...