# Math Idiot question

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I am not the best in math and we have a tutor set up for my daughter but for now I am on my own.

So here is the question she has:

What is a good way to figure out the following type of problem

A group of numbers like 3,4, 7, 11, 17

arrange the numbers into two groups so that the sum of the numbers in each group is equal.

3+ 7 +11= 21 and 4+17= 21

Now she can figure these sorts of problems out by a few trial and error type methods a bit of logical thought but there has to be a better way to figure this out right? I don't ever recall knowing this but frankly I likely wouldn't remember. Google searches reveal nothing because my search terms are too broad, the book doesn't tell us...ugh.

Is this the proper forum for questions like this? If someone has an easy answer I also would like a math program that emphasizes learning how to figure out problems like this. We are using Math Mammoth at the moment to get my daughter up to speed on a few basic math concepts etc.

Edited by lula
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I am not the best in math and we have a tutor set up for my daughter but for now I am on my own.

So here is the question she has:

What is a good way to figure out the following type of problem

A group of numbers like 3,4, 7, 11, 17

arrange the numbers into two groups so that the sum of the numbers in each group is equal.

3+ 7 +11= 21 and 4+17= 21

Now she can figure these sorts of problems out by a few trial and error type methods a bit of logical thought but there has to be a better way to figure this out right? I don't ever recall knowing this but frankly I likely wouldn't remember. Google searches reveal nothing because my search terms are too broad, the book doesn't tell us...ugh.

I think trial and error is the only way, but some logic can put you on the the right answer faster than others.

For example if they have to be equal they you know the two big numbers won't be in the same problem. I would also guess that the two smallest numbers would be in the same problem (given one problem has 3 numbers and the other 4), and would have been wrong there. If there were the same amount of numbers in each problem then I would have guess that the small numbers also would need to be in separate problems.

That said Singapore has a lot of these, and there are times I have to walk my oldest through them, showing her the patterns in the wrong answers and how I use that to find the right answers. She doesn't see it on her own and gets very frustrated. She also randomly picks numbers to try where I systematically start with a group and only change one number at at time, comparing answers to see if I can find patterns.

Heather

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I am not the best in math and we have a tutor set up for my daughter but for now I am on my own.

So here is the question she has:

What is a good way to figure out the following type of problem

A group of numbers like 3,4, 7, 11, 17

arrange the numbers into two groups so that the sum of the numbers in each group is equal.

3+ 7 +11= 21 and 4+17= 21

Now she can figure these sorts of problems out by a few trial and error type methods a bit of logical thought but there has to be a better way to figure this out right?

If it were me, I would add all the numbers and divide by 2 to find out what the sums needed to be. From there it should be pretty straightforward with numbers like these.

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We play games like 24 which have a lot of mental manipulation of numbers. 24 is fun and helps kids see patterns and connections.

http://en.wikipedia.org/wiki/24_Game

We play with a regular deck of cards and make the face cards 11, 12, and 13.

ETA: I realized that I should post how seeing patterns makes a difference:

3,4, 7, 11, 17

arrange the numbers into two groups so that the sum of the numbers in each group is equal.

If you look for patterns, you will automatically see the patterns of 7s in the ones column, the 1s in the tens column, and that 3+1=4. B/c those patterns exist, you know that the two 2-digit numbers will be on opposite sides of the = and that the ones 3,1, and 7 need to be on one side and that 4 and 7 need to be on the other.

That makes it simple to see that 3+7+11=4+17

HTH

Edited by 8FillTheHeart
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Just thinking about some other games that help with these sorts of mental strategies that don't necessarily focus on math but still develop skills:

Qwirkle

Blockus

Set

Pentago

This link has 3 of them if you scroll to the bottom. http://www.amazon.com/MindWare-32016-Qwirkle-Board-Game/dp/1933054395 )

http://www.amazon.com/Pentago-Mindtwister-USA-travel-version/dp/B000YAM0JA/ref=sr_1_2?ie=UTF8&s=toys-and-games&qid=1290340946&sr=1-2

Just wanted to offer some more fun ways to develop these sorts of skills.

(I am so glad I posted this!! I just saw that Pentago now has a family multi-player edition! I know a game I am getting for Christmas!!)

Edited by 8FillTheHeart
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If it were me, I would add all the numbers and divide by 2 to find out what the sums needed to be. From there it should be pretty straightforward with numbers like these.

:iagree: That's how I do it.

Jackie

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:iagree: That's how I do it.

Jackie

I found it interesting that 2 of you responded that you would solve it that way.

It made me curious enough to ask math geeky ds how he would approach it if something like that came up in a math competition. His reply was different again. He answered in a less than a split second and said that it was obvious that the 7 belonged to the 11 and since 18 is 1 more than 17, the 3 belonged to the 18 and the 4 to the 17.

To the OP, obviously there are multiple ways to approach these types of problems. You just need to help your child find the method that makes sense to him/her.

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I found it interesting that 2 of you responded that you would solve it that way.

Well, to be perfectly honest, it's not how I would solve this particular problem. This particular problem I would probably have solved by inspection. But it's the general method I would use if I couldn't immediately figure out the answer to this type of problem.

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