Four fair dice are thrown independently 27 times. Then the expected number of times, at least two dice show up a three or a five, is _________.

The number of words, with or without meaning, that can be formed by taking 4 letters at a time from the letters of the word ’SYLLABUS’ such that two letters are distinct and two letters are alike, is :

A test consists of 6 multiple choice questions, each having 4 alternative answers of which only one is correct. The number of ways, in which a candidate answers all six questions such that exactly four of the answers are correct, is __________.

The total number of 3-digit numbers, whose sum of digits is 10, is __________.