How to calculate the first month of activation of Beijing Unicom's 3G ultra-fast network card?

The monthly subscription fee for 3G speed network card of Beijing Unicom is 50 yuan/month, including 2GB of local Internet traffic in Beijing, 600MB of domestic Internet traffic (excluding Taiwan, Hong Kong and Macao), and 0. 1 yuan /MB of local/domestic Internet traffic. Among them, the first month of activation is charged according to the standard of 0. 1 yuan per megabyte, and the second month is charged according to the 3G fast network card package.