Dmitri has a pair of standard dice; one die is blue, and the other die is yellow. He rolls both of his dice. How many ways could the number on the blue die be larger than or equal to the number on the yellow die?
Consider "tens digit" as blue die and the "ones digit" to be "yellow" die, then we have:
11 , 21 , 22 , 31 , 32 , 33 , 41 , 42 , 43 , 44 , 51 , 52 , 53 , 54 , 55 , 61 , 62 , 63 , 64 , 65 , 66 , Total = 21 ways
Or: Probability is: 21 / 6^2 =21 / 36 = 7 / 12
