Answer sheets to a 19th century state examination have been found on the backside of a folding screen kept at Changdeok Palace in Seoul.

According to the National Research Institute of Cultural Heritage, the discovery was made while the four-panel screen named the "Sun, Moon and Five Peaks" was undergoing preservation that began in 2016. 

Dozens of answer sheets belonging to an 1840 state exam are believed to have been penned by test takers who did not pass the exam. 

In those days, those who passed received their answers back but papers collected from those who didn't were recycled. 

Korea University research professor Yoon Seon-yeong said the recycling indicates paper supplies were not sufficient even at the royal court in the latter days of the Joseon Dynasty.

Yoon said that based on the discovery, the folding screen must have been made at least after 1840.