Count up all the throws that are possible and record how many times each total appears.

You may have When these data are plotted you have the ideal surface of distribution in Plate XX.

All this means that when you throw three dice you are just as likely to get any one combination as any other.

But you are more likely to get a total of 10 or 11 than 3 or 18.

You can express this likelihood by the expression 27 to 1, for there are 27 combinations that will give a total of 10 or 11, whereas there is only one combination that will give 3 or 18.