CM Math Book One Experimental Problems p 123/128

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  • December 17, 2019 at 11:14 am
    Dickeyfamily
    Participant

    Hello,

    I am working through book one with my first grader.  The experimental problems started popping up and at first, when they were all addition, things were fine.  But then on page 123 the problem reads: 3-1+3 (Problem #1, Pure Number) and page 128 has 14-3+6 (Problem #7, Pure Number). I should preface all of this to say I was not a math major.  But I do recall an order of operations PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction) which states that addition must be done before subtraction in a complex mathematical equation.  So for 3-1+3, you would perform 1+3 first, which is 4, then the problem would be 3-4=-1.  And for the other one, (14-3+6) it would be 3+6 first since Addition comes before Subtraction which is 9, and 14-9=5.  The answer key indicates the answer to the this one is 17 and the former is 7 which isn’t what I got. This led me to a nice conversation with my 6 year old about order of operations but am I even correct about all of this?  If so I wanted to point it out so you can revise future editions, but if not, I guess I will teach him to perform the operations from left to right.  Thank you in advance for your time in reading this ramble.

    December 17, 2019 at 3:49 pm
    Richele Baburina
    Participant

    Hello Mrs. Dickey,
    Thanks for the note (I smiled that you called it a ramble as I hadn’t read it as such). I thought there was a tip or note of instruction on this in the book so my apologies if there isn’t. This isn’t meant to be PEMDAS but mixed-operation problems that are taken orally with pauses in-between (much like dictation). You’ll see more of them with five or more figures in Book 2, especially fun for mental math. hth
    Warmly,
    Richele

    December 17, 2019 at 7:42 pm
    Richele Baburina
    Participant

    I do want to note that even with PEMDAS, addition and subtraction are taken left to right in order that they appear (as is multiplication & division). If one wanted to say something different, that’s when parenthesis would be used but we aren’t getting into that yet. Perhaps PEMDAS needs to be PE   MD   AS. hth

    December 17, 2019 at 8:19 pm
    Dickeyfamily
    Participant

    Thank you so much Richele!!! I didn’t google it because I have the personality type that doesn’t comprehend as well when reading instructions (clearly as I missed the instructions there).  This makes sense and thank you for the reminder about addition and subtraction.  This has been fun relearning key skills!

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