Harvey has a fair eight-sided die that has a different number from 1 to 8 on each side. If he rolls the die twice, what is the probability that the second number rolled is greater than or equal to the first number? Express answer as a common fraction.
On the first roll, every number has a 1/8 chance to be rolled
On the second roll, a lower number on the first roll has a greater chance to have a higher number rolled or the same number the second time.
First roll is... 1 : probability to be out rolled or equal roll 8/8 or 1/1 2 : probability to be out rolled or equal roll 7/8 3 : probability to be out rolled or equal roll 6/8 or 3/4 4 : probability to be out rolled or equal roll 5/8 5 : probability to be out rolled or equal roll 4/8 or 1/2 6 : probability to be out rolled or equal roll 3/8 7 : probability to be out rolled or equal roll 2/8 or 1/4 8 : probability to be out rolled or equal roll 1/8