It’s easy to snap pictures of anything these days, because so many phones can work like cameras. In the old days, taking a picture was so hard! The light bounced into a black box, where it hit a clear plastic film covered in chemicals. It took time for the chemicals to change color, so the person in the photo had to stand still for whole minutes without moving at all. Now it all happens in a split second with electronics. So our fan Yuri R. S. asked, how many pictures are taken every year around the world? Unbelievably, it’s 1 trillion or more (1,000,000,000,000). But with almost 7 billion cell phones out there, that comes to only about 140 photos per person per year. When that many people are snapping selfies, the photos stack up fast!
Wee ones: The lens of a camera (where the light goes in) is usually a circle. See if you can spot 3 circle shapes in your room.
Little kids: If you take 1 picture each day this week, how many do you take? Bonus: If you take pictures of 2 people, and each of them takes pictures of 2 people, how many people got to pose for a picture?
Big kids: There are 8 billion people in the world, and 7 billion cell phones. If 2 billion people each had 2 of those phones, how many people would have no phone at all? Bonus: If 300 million Americans each took 10 pictures this week, how many pictures would that come to?
Wee ones: Answers might include buttons, shoelace holes, the bottom of a cup, or the face of a clock.
Little kids: 7 pictures. Bonus: 6 people, since you took pictures of 2 and your friends took pictures of 4 more.
Big kids: 3 billion people. The 2 billion people would have 4 billion of the phones, leaving only 3 billion more phones for 3 billion more people. Only 5 billion total would have a phone. Bonus: 3 billion pictures.
Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.