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jmc

prealgebra senior

Problem

Nancy generates a two-digit integer by rolling a six-sided die twice. The result of her first roll is the tens digit, and the result of her second roll is the ones digit. What is the probability that the resulting integer is divisible by 8? Express your answer as a common fraction.
Solution
The largest number Nancy can generate is 66. The positive two-digit multiples of 8 less than 66 are 16, 24, 32, 40, 48, 56, and 64. 40 and 48 cannot be produced from the numbers on a 6-sided die, but the other 5 multiples of 8 in the list can. Therefore, there are 5 equally likely ways to produce a multiple of 8 out of the total combinations for the two dice, so the desired probability is .

(Special thanks to 5849206328x for this solution.)
Final answer
\dfrac{5}{36}