Lately, I’ve been involved in AMC (Australian Mathematics Challenge). These are some of the actual questions in the question booklet.

THIS IS ONE GREAT MATHS CHALLENGE.

Every minute, the first letter of each word goes to the back of the word. In how many minutes will the sentence appear again?

Solution:

After one minute, it will become this:

HIST SI NEO REATG ATHSM HALLENGEC

So,

THIS: 4 minutes

Is: 2 minutes

ONE: 3 minutes

GREAT: 5 minutes

MATHS: 5 minutes

CHALLENGE: 9 minutes

To get the answer, you have to get the LCM of the number of minutes each words take to reform.

LCM: 180 minutes

The answer is 180 minutes.