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4 X 4 + 4 X 4 + 4 - 4 x 4

can you please break this very simple problem:

4 X 4 + 4 X 4 + 4 - 4 x 4 =

 

I am old and I forget stuff. :) Thank you!

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I'm just a 30+ year veteran home school mom, age 57 but I'm pretty sure this is correct after all those years teaching algebra, lol:

Order of Operations:

4x4+4x4+4-4x4=

Multiplication and Division, left to right:

(4x4)+(4x4)+4-(4x4)=

16+16+4-16=

Then Addition and Subtraction, left to right:

32+4-16=

36-16=20

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6 Answers

Order of Operations

PEMDAS

Parenthesis

Exponents

Multiplication

Division

Addition

Subtraction

all problems are read left to right

step 1 Check for grouping symbols like parentheses

none present

step 2 check for exponents, There are none as written but note: any thing multiplied by itself is by definition exponential: a*a=a^2

the symbol ^ means to the power of so we pronounce this a to the power of 2 or a squared.

the 2 comes from the fact that there are 2 a terms being multiplied. 

another way to write this equation is

4^2+4^2+4-4^2

so we simplify the exponents:

4^2=16

so

16+16+4-16

you can do this 2 ways

1. add then subtract 

16+16= 32+4 = 36-16=20

2. by the commutative property of addition you can commute one of the +16 terms to be next to the negative 16, if you look at it like everything is addition and you are adding a negative to a positive instead of subtracting.

so you are actually re-writing the equation as 

16+4+16-16

a-a = 0

any number minus itself equals zero

16+4+0 or 16+4 = 20

or you can look at it this way 4 x 4 = (4+4+4+4)

so (4+4+4+4)+(4+4+4+4)+4-(4+4+4+4) this is really 4*9-16=36-16=20.

Math is how you look at it. There are so many ways to solve one problem. as long as you play by the rules and you don't "cheat" :D it is a great way to get students to think outside the box, problem solve and critically think. these are all vitally important skills in life.  I hope you liked my explanation of question. If you are interested in tutoring, please look me up on wyzant,  http://www.wyzant.com/tutors/TheTechTutor.

Thanks for your time.

Sincerely,

Ian F.

The TechTutor

Remember to keep with order of operations! Multiply before addition or subtraction.

4x4+4x4+4-4x4 multiply all first

16+16+4-16 "cheat" 16-16=0

16+4=20

Order of operations says you should do the multiplication first in this problem. In order to help see where the multiplication is, you can put parentheses around them, like so: (4 x 4) + (4 x 4) + 4 - (4 x 4). 4 x 4 = 16, so (4 x 4) + (4 x 4)  + 4 - (4 x 4)  = 16 + 16 + 4 - 16. Two of the 16's cancel each other out, so 16 + 16 + 4 - 16 = 16 + 4 = 20, so 4 x 4 + 4 x 4 + 4 - 4 x 4 = 20.

 

You're right! It's very simple.

4 X 4 + 4 X 4 + 4 - 4 x 4 = 16+16+4-16 = 20

I suggest you use a calculator if you want the final answer fast, not the explanation and the method

Think of it as four groups of four plus another four groups of four. Then add four more to the sum. Then take away four groups of four. Always multiply before adding or subtracting. Multiply the numbers which are "touching" the X. So, four groups of four are sixteen and the other four groups of four are also sixteen. Sixteen plus sixteen is thirty-two. When you add four more, you'll have thirty-six. Now we'll take away the other four groups of four (sixteen). What is thirty-six minus sixteen? Twenty, right? I always like to take think of equations in concrete terms and talk it out to myself to really comprehend the idea. Hope this helps.