Other sites let you use the Google Authenticator app to generate the six-digit number. The app generates a different six-digit number for each connected site, and these numbers change every 30 seconds. With the app, you don't have to wait a few seconds to receive a text message.
Factors that cause population growth include increased food production, improved health care services, immigration and high birth rate. These factors have led to overpopulation, which has more negative effects than positive impacts. Keep Learning.
Impact on Population Size and Age. 1  New immigration (legal and illegal) plus births to immigrants added 22.5 million residents to the country over the last decade, equal to 80 percent of total U.S. population growth. 2  Recent immigration has had only a tiny impact on the nationâs age structure.