perplexus.info :: Numbers : Class act

Class act (Posted on 2002-05-02)

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.

See The Solution Submitted by theBal

Rating: 3.6364 (11 votes)

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Solution

Comment 16 of 16 |

The wrong students were 16 and 17. The smallest possible number is 2^3*3^3*5^2*7*11*13*19*23*29*31=2123581660200.

Edited on July 13, 2019, 8:55 pm

Posted by Math Man on 2019-07-13 20:26:58

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