CS 100 (Learn) — CS 100 (Web) — Module 04
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Note: This video transcript has been slightly modified. Corrections are marked with strikethrough, and alternative wording has been placed in [square brackets] to correct some of the awkward or confusing phrasing in the videos.
In this video we are going to have a short conversation about the order of operations, and how to make sure that we enter formulas correctly into Excel.
Right now just stop for a second and I want you to think what is: "3 plus 6 times 2"... what result did you get did you get? 15 or 18?
Let's look at how both answers could be correct if you had written "3+6*2" (that is the way I said it) then you would use your order of operations, which some of you remember: Brackets Exponents Division Multiplication Addition and Subtraction (BEDMAS), [which] helps us [know] what order to do things.
In this [example] we are going to do the 6 times 2 first, and we get 12, and then we add 3 and then we get 15.
However, you could have written the original formula as "3+6" and then interpret the whole thing times 2. In this case (again following BEDMAS) we have to do it [in] order: first we do what is inside the brackets. That would be 3 plus 6, [which] equals 9. Then we multiply that times 2 and then we get 18.
The problem arose because [of] the way I said it verbally: there was no way to know for sure which interpretation I actually wanted.
That is why in mathematics we have two [tools]: we have our order of operations, and we use brackets to [ensure] we do things in the correct order.
[In] Excel, we can enter both formulas and see that it calculates the results correctly. First, "=3+62" will show us [the value] 15. [Alternatively,] "=(3+6)2" will show us [the value] 18.
[By] looking at the formulas, we can see how to use brackets and Excel formulas to make sure that the order of operations is done correctly.
In mathematics, when you have an expression [such as] "1+1" the fancy term we have for the plus sign is an operator. [Additional] operators you are familiar with are (addition), subtraction, multiplication, and division.
Another important operator is exponent. If you want to write "2 [raised] to the 3", it should produce 8.
In Excel that operator is the little ^ [and it] is called a caret. It is above the number 6 on most keyboards. If enter the formula "=2^3", it means 2 times 2 times 2, which is 8.
That is probably the only operator you may not have been familiar with and it is worth mentioning right now so we have all the standard operators: addition, subtraction, multiplication, division, and exponentiation.
Now you are ready to start entering formulas in Excel.