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.
The aging of the world's population is the result of two factors: declines in fertility and increases in life expectancy (2). Fertility rates declined in developing countries during the preceding 30 years and in developed countries throughout the 20th century (2).