Probability: Fun with Grandchildren

By on Apr 29, 2013 in Playtime | 7 comments

Share On GoogleShare On FacebookShare On Twitter

What Is the Luckiest Number in Dice? Fun with Grandchildren


American, Chinese, and casino dice
American, Chinese, and casino dice (Photo credit: Wikipedia)

Your grandchildren may play board games that use two dice, like Parcheesi, a current grandchild favorite. Have you ever wondered what is the most common number you can get when you roll two dice and add them together, or if there even is a number that comes up more often?

Here is an easy way to show that you can predict the most common sum of two dice.



What Should Happen?

The most M&Ms will be on the squares with 7 in the middle. Why?

There are more 7s than any other number. If you look at the grid, you will see there are:

Another way to look at this distribution is:

The more occurrences there are of a number, the more likely, or probable, that that number will be rolled with the dice. Thus, the sum of the numbers that equal 7 is going to come up more often when you roll the dice.


Why Is This Important?

Probability is used in weather prediction. The National Weather Service, for example, provides a color-coded map of the probability that different areas of the country will have more than one inch of snow in the next 24 hours. While on any given roll of the dice, the number could be any of the numbers on the grid, on average, 7 will come up more often. The same way, on any given day, it may or may not snow, but, on average, the weather service can predict when it is likely to snow.

Thank you to for this activity.

Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers”

Don’t forget to follow Grandmother Diaries via Geek Girl on Facebook and Twitter. Sign up for updates by email!