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JavaScript JavaScript Basics (Retired) Working With Numbers Numbers and Strings

CHARLES REROMA
CHARLES REROMA
771 Points

When using ( ) in computations...

So I'm working on a challenge on this path and I got an error, basically I wanted to compute two values first thats why I placed them inside the ( ) but then I got a wrong answer. So my question is,

What is the difference between the two below?

var wholesalePrice = 5.45; var retailPrice = 9.99; var quantity = 47; var salesTotal = retailPrice * quantity; var profit = salesTotal - wholesalePrice * quantity;

var wholesalePrice = 5.45; var retailPrice = 9.99; var quantity = 47; var salesTotal = retailPrice * quantity; var profit = (salesTotal - wholesalePrice) * quantity;

2 Answers

Jennifer Nordell
seal-mask
STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Hi there! Let's take a look a closer look at the computations. This is all based on the order of operations that you probably learned in math class in middle school sometime. But, many of us don't have to use it on a day to day basis so it gets easily forgotten. I was always taught the phrase "Please Excuse My Dear Aunt Sally" to help remember them. Parentheses, exponents, multiplication, division, addition, and subtraction. Parentheses are done first. Exponents are done second. Multiplication and division come 3rd, and addition and subtraction come 4th. If two operations are on the same "level" of importance (multiplication/division and addition/subtraction) then they are done from left to right.

salesTotal in both examples is calculated to be 469.53

In your first example (substituting the values in for the variables):

  • Profit equals wholesalePrice times quantity subtracted from salesTotal
  • wholesalePrice times quantity is equal to 256.15
  • profit is then equal to 469.53 - 256.15
  • profit is equal to 213.38

In your second example:

  • First, we subtract wholesalePrice from salesTotal
  • The result is 469.53 - 5.45
  • This gives us 464.08
  • Then we multiply that by the quantity of 47
  • 464.08 * 47
  • Profit would then equal 21,118.76

As you can see, the order of operations can greatly skew the results.

Hope this helps clarify things! :sparkles:

Aiden Campbell
Aiden Campbell
6,618 Points

It should work, I pasted your comment into my chrome console and I was able to get a number for profit so it looks like it works, make sure you are entering it correctly on whatever text editor you are using.