# Public school math is confusing...

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43 + 67

+__ -__

45 + ____= _____

43+67

+______-_______ <------- No freaking clue at all....

45+65=110 <-------Maybe that is what they are wanting there?

The top one, I know, they are just breaking it down to tens plus ones... so they can learn to mentally add quickly. My daughter (10) has been exposed to that in little bits over the years.

The second one, I started to say I had no clue, but I think what they are doing is mentally rounding the 43 to the nearest five (by adding two)... so you have to subtract two from the sixty seven.... to get 65... this way you can mentally add 45+65 = 110 easier than you can mentally add 43 + 67 = 110.

I, personally would have rounded to the nearest ten instead of five... So I would have added 7 and subtracted 7, to get 40+60 to get 110 MUUUCH easier.

As a side note, my daughter is getting primed to move onto algebra next, so I've had some more experience with this level of mental math. Prior to that, I would have had no clue.

It's partially rounding and it's trying to get the kids to understand how their brains break down a math problem so they can do it mentally... At least that's what I'm gathering because it keeps saying, use mental math...but it wants you to put out all the answers...

So it's

43= 40+3__+67=60+7__

and then you solve it backwards...3+7= 10, 40+60=100. 10 can't be in the 1's place and 100 can't be in the 10's so you carry everything and you get 110.

That was ONE of the ways they had to solve it.

The other way was to subtract 2 from 67 and add it to 43 so you're new problem would be 45+65 and then do all that crazy stuff above.

It took me awhile to understand what they were showing, but I don't know how to explain so she understands it. I also have NO clue how a parent that doesn't know what they're doing is supposed to know how to help them unless they're sitting down and spending a ton of time trying to figure out themselves too.

I know she doesn't understand what she's doing because she couldn't answer the critical thinking question at the bottom of the page, Why is it easier to add some numbers than it is others? It took me another 20 minutes of showing her more problems and talking her through the answer before she finally understood the answer.

Quoting calimom1123:

This is exactly what I was thinking. Bju learns similar to this. The other part im not sure because we do it this way..

43+67

67+3=70

43-3=40 answer is 110.

You round 1 number to the closest tens then subtract the same amount it took to get there. Does that make sense?? Not sure how they got 45 though.

Quoting soy_latte:Is it suppose to be getting them to add large numbers by rounding?

43 = 40 + 3

67 = 60 + 7

43 + 67 = 40 + 60 + 7 + 3

I was able to figure it out, but I don't know how to explain it at a level she can udnerstand it. Know what I mean? I've tried showing her with blocks, writing it with her on a marker board, and doing just random problems that were even easier than those on her worksheets... She's not grasping it at all and I'm running out of ideas.

Quoting KrissyKC:

The top one, I know, they are just breaking it down to tens plus ones... so they can learn to mentally add quickly. My daughter (10) has been exposed to that in little bits over the years.

The second one, I started to say I had no clue, but I think what they are doing is mentally rounding the 43 to the nearest five (by adding two)... so you have to subtract two from the sixty seven.... to get 65... this way you can mentally add 45+65 = 110 easier than you can mentally add 43 + 67 = 110.

I, personally would have rounded to the nearest ten instead of five... So I would have added 7 and subtracted 7, to get 40+60 to get 110 MUUUCH easier.

**My son brought that home last week and I looked at it and thought, what the hell is this? Asked son what he had to do and he gave the same answer she did, "no idea mom." Needless to say, my brother helped ds and I with homework that night. He is a teacher.**

RIGHT?! That's what I was thinking. I was happy I was able to figure it out yesterday, it's just explaining it so it makes sense to an 8 yr old is what seems impossible!

Quoting kirbymom:

Holy mamma! What kind of math is this?! I have never learned this and couldn't even begin to try and help explain it. This new fangled way of doing math would make me look like I was dumber than a bag of bricks. Even though I am not that bad. :) I am sorry for not being able to help you. :(

Yes she's in the public/private school out here.They all use the same curriculum...not sure what math program they're using specifically though. They don't have a book to bring home, just worksheets, and no explainations for the parents (or babysitters in my case).

I did have her do easier problems with me, but she's still struggling. I think I finally made some progress though when I had her say the number outloud and write it at the same time so if she said 473 she was actually saying and writing 400 70 3 and was able to break the first part down. But trying to explain that this is how they want your brain to compute this is not making any sense to either of us lol

Quoting romacox:

That is the new math, which teaches math concepts. Even if the children get the right answer, the school system counts it wrong if they did not do the process as wanted. College professors complain that public schooled kids are entering college not knowing how to do basic math. I think it is because of the new math. It does not teach analytical thinking.

But it sounds like she is not homeschooled. So you will need to teach her the "new math" used in public schools. I would break the problem down in smaller pieces, and take one step at a time using objects (such as pennies or blocks as you mentioned). Also I would start out with smaller numbers, and work up to the larger numbers. Make it as experiential as possible.

can he explain the concept to me ?? LOL What is the point behind it other than to confuse the parents/gaurdians?? LOL

Quoting cowboygal:My son brought that home last week and I looked at it and thought, what the hell is this? Asked son what he had to do and he gave the same answer she did, "no idea mom." Needless to say, my brother helped ds and I with homework that night. He is a teacher.

**Add your quick reply below:**

- chotovec82

Bronze Member on Oct. 10, 2012 at 5:54 PM43 = ____ + 3

+67 = _____+__

___ = _____+____+_____Actually I think I do understand this:

43=40+3

67=60+7

110=100+7+3

I don't think I understand the next part. I'll try tho.