The Public Service Commission (PSC) has allowed the use of calculators in some subjects in the written test of the 35th BCS examinations. The subjects are mathematical reasoning, mathematics, applied mathematics, physics, applied physics, statistics, accounting, computer science, and the subjects related to engineering and electronics, the PSC said in a statement yesterday. But the use of the device would not be allowed for the tests of other subjects, it said. Earlier on July 26, the PSC banned calculators and other electronic devices at the examination centre. Calculators are also banned in the BCS preliminary exams. According to the schedule, written test for compulsory subjects will take place between Sep 1 and Sep 7 and post-related examinations between Sep 9 and Oct 10. This year, 20,391 candidates, who cleared the preliminary tests held on Mar 6, will sit the written tests across Bangladesh. The PSC on Sep 23 last year had announced the 35th BCS exams to fill up 1,803 positions. The average pass mark is 50 percent, but scoring less than 30 in any subject will count as zero marks.