27. The mobile phone number consists of 11 digits, where the first 3 digits are the network identification number, the middle 3 digits are the area code, and the last 4 digits are -
A. Area identification number
B. Area code
C. User ID number
D. User number
【Answer】D
【Analysis】Currently, the mobile phone numbers used in our country consist of 11 digits, which is the longest mobile phone number globally. Our mobile phone numbers can be divided into three segments, each with different coding meanings: the first 3 digits are the network identification number, digits 4-7 are the regional code (HLR Home Location Register), and digits 8-11 are the user number (randomly assigned). This configuration maximizes the utilization of number resources, preventing waste, and allows for flexible allocation among different operators and regions, effectively addressing the issue of number segment capacity. Theoretically, 11 digits can provide 100 billion combinations. Removing the fixed "1" at the beginning, 10 digits can still accommodate 10 billion different numbers, which is more than enough for the 1.4 billion population, allowing for about seven to eight numbers per person.