Maths challenge

Gimme 5

On a digital clock showing "24-hour time", over a whole day, how many times does a 5 appear? Is it the same number for a 12-hour clock over a whole day?


170, counting hours and minutes. However, if you were to count how many fives when you look at the clock every minute (so, for example, at 05:53 there are two, then at 05:54 there are two, and at 05:55 there are three and so on) it would be 504 times. This isn't including seconds of course!

The answer is the same for a 12-hour clock.

There are many puzzles to be found on the NRICH website,

The NRICH Maths Project provides a free monthly online magazine containing articles, problems, puzzles, games and challenges suitable for all ages. It provides resources for maths clubs, home users and teachers.

Log in or register for FREE to continue reading.

It only takes a moment and you'll get access to more news, plus courses, jobs and teaching resources tailored to you