31 students in a row were numbered 1,2,...,31 in order. The teacher wrote down a number on the blackboard.

Student 1 said "the number is divisible by 1",
Student 2 said "the number is divisible by 2",
and so forth...until
Student 31 said "the number is divisible by 31".

The teacher remarked: "Very well pups, but two of you gave a wrong statement, and those two sit besides each other". Determine those two.

Every number is divisible by 1, so student 1 is telling the truth. <br><br>
Students 2 and 31 can't both be wrong because they don't  sit next to each other.<br>
If student 2 is wrong, then so is student 3.<br>
If student 31 is wrong, then so is student 30.
  

Posted by bob909 on 2004-09-07 15:57:03