While we were at lunch last week, The Ten-Year-Old’s mind turned to fractions, as fifth grade minds are prone to do. She had learned in school that the top number in a fraction is called a numerator, while the bottom number is the denominator, but the line in the middle didn’t seem to have a special name.
That was disappointing.
“Mommyo,” she asked between bites of grilled cheese. “What’s the line in a fraction called?”
This was easy.
“Division bar,” I said.
“Fraction bar,” Daddyo said at the same time.
Gran chimed in with something that started with v, but I didn’t catch it.
So I decided to look it up. Turns out that little line has lots of names. People frequently refer to it as the:
- division bar
- fraction bar
What’s a vinculum?
I had never heard of vinculums before, so I did a little research on them. Merriam-Webster defines a vinculum as
a straight horizontal mark placed over two or more members of a compound mathematical expression and equivalent to parentheses or brackets about them
Put more simply, a vinculum is a horizontal line placed over a group of math terms to show that they are related to one another.
Even simplified that definition sounds really broad, and like vinculums might appear in lots of other places besides fractions.
Where else can you find vinculums?
Mathematicians use vinculums to designate:
- Vinculum (Wolfram Math World)