Photograph of an alarm clock with a digital time display.

Explorations and Games

Learning Goals:

  • Develop and apply reasoning skills to make and test math predictions
  • Communicate mathematical thinking orally and visually

The Challenge:

On a digital clock showing 12-hour time, over an entire day, can you figure out how many times the digit 5 appears?
What about the digit 9? The digit 1? The digit 0?

Why do you think some of these digits appear more or less than others?

Questions and Prompts to Support your Child:

  • What was your process for figuring out the total appearances of each digit? Did this plan change after you found the total for the first one?
  • Could your work on some digits help you work through another digit more easily?

Extensions & Adaptations:

  • How would this challenge change if you only found the totals that each digit appears while you are awake?
  • How would this challenge change if the clock was showing 24-hour time? Which digits would now appear more often?
  • Which would now appear less often?

Source: NRICH Math