Infinity

Infinity means something without an end. If you try to count forever, you will never reach infinity. It is not really a number you can write down. Instead, it is an idea about things that go on and on. Math uses infinity in many ways.

The Symbol

Infinity has its own special symbol. It looks like the number 8 lying on its side. The symbol was first used about 400 years ago. Today, you see it in math books and problems. It reminds us that numbers can keep going forever.

A number line that keeps zooming in to show numbers going on forever.
A number line that keeps zooming in to show numbers going on forever. (Taken by M.Romero Schmidtke for Enciclopedia Libre en español / Wikimedia Commons)

Where We See It

You can count 1, 2, 3, and keep going, but you will never stop. The numbers go on to infinity. Between 0 and 1, there are also infinite numbers like 0.1 and 0.01. Space might be infinite too. The idea of infinity is very big and fun to think about.

Fun Facts

  • The infinity symbol is called a lemniscate.
  • There are different sizes of infinity in math.
  • Some mirrors facing each other can make an image look like it goes on forever.

Did You Know?

A math thinker named Georg Cantor proved that some infinities are actually bigger than others.