Have you ever taken a math class?

And then you’re probably familiar with the order of operations, right?

It’s commonly used in algebra. Basically it says that…

  • Parentheses come first. Use them to give a higher order of precedence to a part of your equation. 
     
  • Multiplication & Division come next (in order of left to right). 
     
  • Addition & Subtraction come last (also left to right).

So 2*27+19-78 will start by multiplying 2 by 27. But if you use parentheses like this…

2*((27+19)-78)

…then your multiplication happens last!

History Lesson

So where did this order of operations come from? Whose fault is it? =^)

  1. 1960s - As mathematicians began writing books about algebraic notation, they basically agreed on the idea that multiplication would take precedence over addition. It's a natural hierarchy that lends itself well to writing polynomials with as few parentheses as possible. So at a time when the authors of these books on mathematics had to begin their book with a list of conventions... it wasn't needed on the basic order of operations... they all seemed to have agreed.  
     
  2. 1964  -   In Van Schooten's 1646 edition of Vieta, B in D quad. + B in D is used to represent B(D^2 + BD).     
     
  3. 1800s - The term "order of operations" was starting to get used in textbooks. It was used more by textbooks than mathematicians. The mathematicians mostly just agreed without feeling the need to state anything official.
     
  4. 1920s - In this time period, the mathematicians were debating about whether or not multiplication should take precedence over division. Although they'd still argue over who won this argument, today it's become most common (and taught predominantly) that multiplication and division are equal, read from left to right. The reasoning is to keep it simple and to let the parentheses do it's thing!

 You'll still find textbooks that don't fully agree with each other, but the basics are commonly set now, and the world is full of order and peace, thanks to the Order of Operations!

   - User Ed