Faced with delays and complaints of overly difficult questions, Israeli students yesterday took the mathematics matriculation exam amid unusual circumstances. The difficulties owed to measures aimed at preventing foul play following the alleged theft of one exam form. In some schools the test was delayed by one hour, after the Ministry of Education decided at the last-minute to toss out the exam which was leaked, and use an alternative test which it hastily distributed to schools via computer. Some students who took the replacement exam complained that it was unusually difficult. Education Minister Gideon Sa'ar said yesterday at a conference in Ramat Hasharon that he was pleased with his ministry's performance through the leaked test affair.