What is Bar Notation in Math? - Definition & Examples

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  • 0:03 Who Is Mom's Favorite?
  • 0:20 Forever and Forever
  • 0:38 Forever and Forever in Math
  • 2:09 When Not to Use Bar Notation
  • 2:30 Lesson Summary
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Lesson Transcript
Instructor: Mark Boster
Some numbers with decimal points could go on forever. Bar notation is a way to show a repeating number and is much quicker than writing all those numbers over and over again!

Who Is Mom's Favorite?

''Mom loves me best,'' Tony says.
''No way, I'm Mom's favorite,'' Sarah argues.

Have you ever had this argument with your brother or sister? Well, when you ask Mom, she'll say that she loves you both the same. You know that. The answer to how long will she love you is infinity!

Forever and Forever

There is a symbol that stands for infinity. Infinity means that something goes on forever. For example, numbers go on forever. You can add 1 to any number to get a higher number. Look at the symbol and follow it around and around with your finger. You never get to the end of it. It goes on forever, infinitely.


Forever and Forever in Math

Sometimes in math there are numbers that go on forever. Most of the time, they repeat the same numbers over and over again. For example, some solutions for division equations go on forever. They repeat, and continue to repeat, on and on and on.

Here's an example for you:

1 / 3 = 0.33333333333333333333333333333333333333333333333...

The 3s could go on forever. You could spend the rest of your life writing 3s and you still wouldn't reach the end. The 3s go on for infinity. It just doesn't make sense to spend the rest of your life writing 3s, so in math we would say 1 / 3 = 0.3 with a line over the three to show that the three repeats forever. This is called bar notation. Bar notation is an easier way to write a repeating number by putting a line, or bar, over the repeating numbers.


Here's another example. 1 / 7 = 0.142857142857142857142857142857...

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