SOLUTION: the problem is 5 + 5 + 5 - 5 + 5 + 5 - 5 + 5 x 0 = ? I say it should be 0, my son and grandson say 15 because you do the multiplcation first and that takes away the last 5. I kn

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Question 644048: the problem is 5 + 5 + 5 - 5 + 5 + 5 - 5 + 5 x 0 = ?
I say it should be 0, my son and grandson say 15 because you do the multiplcation first and that takes away the last 5. I know you multiply first
But when I went to school many, many years ago, I was taught there would have to be ( ) around the 5 and the 0 to make it a separate quantity. Therefore, since there are no ( ) the 0 applies to the entire line.
Is this something the new math taught, not having the ( ) like grammar taught now changes rules I learned?


Found 2 solutions by MathTherapy, katbit:
Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
the problem is 5 + 5 + 5 - 5 + 5 + 5 - 5 + 5 x 0 = ?
I say it should be 0, my son and grandson say 15 because you do the multiplcation first and that takes away the last 5. I know you multiply first
But when I went to school many, many years ago, I was taught there would have to be ( ) around the 5 and the 0 to make it a separate quantity. Therefore, since there are no ( ) the 0 applies to the entire line.
Is this something the new math taught, not having the ( ) like grammar taught now changes rules I learned?

You are right in that you do parentheses first, hence the ACRONYM, PEMDAS, or as we say:
PLEASE
Excuse
My
Dear
Aunt
Sally

As you can see parentheses come first, which means that the operation in parentheses should be done first. However, in this problem, you have to realize that there are three signs (+, - , and *). You would then have to place the parentheses around any operation that needs to be evaluated before others, of which the last 5 and zero are a part of. Therefore, you have to enclose this operation (5 * 0) yourself, thereby reminding yourself that that operation has to be done first. So, bottom line is, a pair of parentheses need to be there, but you can choose to place them there, or don't place them, but remembering that that operation, or any other operations (parentheses, exponents, multiplication, and/or division) have to be done before addition and subtraction.

Your son and grandson are 100% correct.

Send comments and “thank-yous” to “D” at MathMadEzy@aol.com

Answer by katbit(6) About Me  (Show Source):