Find the indicated probability rolling 2 number cubes ; p (rolling doubles)

The probability of rolling two dice with the six sided dots such as 1, 2, 3, 4, 5 and 6 dots in each die.

When two dice are thrown simultaneously, thus the number of events can be 62 = 36 because each die has 1 to 6 number on its faces. Then the possible outcomes are shown in the below table.
(i) The outcomes (1, 1), (2, 2), (3, 3), (4, 4), (5, 5) and (6, 6) are called doublets.
(ii) The pair (1, 2) and (2, 1) are different outcomes.

Probability – Sample space for two dice (outcomes):

If the diameter is 8 than the radius is 4 because 2r or 2*radius equals the diameter. 4*2=8. 8/2=4.