The document is calculating the probability of randomly selecting a 5-digit number greater than 65,000 where the numbers cannot be repeated. It does this in two steps:
1) It calculates there are 1,344 possible 5-digit numbers between 65,000 and 65,999.
2) It then calculates there are 9,075 possible numbers between 70,000 and 99,999.
Adding these together gives a total of 10,416 possible numbers greater than 65,000. It then divides this by the total number of possible 5-digit numbers (90,000) to calculate the probability as 11.57%.