We know that numbers are useful. We rely on them to analyze global economic trends, but also to count calories, create passwords, manage schedules and track our spending. Numbers give order to the chaos of our lives. And that means we can use numbers to reflect, learn, and re-discover ourselves.
We’ve launched a new YouTube series called ‘My Favorite Number,’ that shows how a single digit can give us unique insight into global development and humanity. A number can have a profound effect on human lives.
We asked economists here at the World Bank, “What is your favorite number?” and we were surprised to find that the numbers they chose actually impact all of us in unique ways.
Let’s start counting.
1. Rachel Kyte: 2 Is a Small Number with Big Problems 
Rachel Kyte, Vice President of Climate Change, tells us why 2 has the power to change the world in which we live. If the world warms by just 2 degrees Celsius we’re going to see a major shift in weather patterns that will endanger cities, livelihoods and even lives. But 2 could also help us solve the problem. Watch and learn how:
2. When It Comes to Prosperity, 40 Is Key  
For Kaushik Basu, Chief Economist at the World Bank, 40 is a number that has taken over his life. When it comes to shared prosperity, the key indicator is how the bottom 40% of any population prospers. Watch and learn how:
For more videos, visit the World Bank YouTube Channel .