## Day 2 of school and I’m already stumped by my kid’s math problems.

September 3, 2008 by K. Trainor

Eesh. Am I that stupid? That inadequate? I can maintain two businesses and three checkbooks but I can’t do 8th grade math? The problem that threw me off was this one:

**If you had 100 sugar cubes, how many would it take to build the largest cube possible out of them?**

Try it. It’s not as easy as it sounds. Now I know there’s a mathematical principle involved here. Some simple formula any math geek would know. But in my husband’s absence and with no personal membership to Geekdom, what’s a Mom to do?

Aha! The Rubik’s cube!* <Send daughter off on mad errand to unearth one for visual reference.>* It’s 3 cubes by 3 cubes. So that’s 9. In 3 layers of 3. So wait–is that 27 times 3? Or divided by 3? No…that’s 9 again.

Answers…I need answers.

**If you build it, they will come.**

LEGOs! *<ding-ding-ding! What do we have for her, Johnny?>* I caught myself laughing like Snidely Whiplash. (If you’re too young to know who Snidely Whiplash is, please don’t tell me. My self esteem’s taken a big enough hit today.)

“Uh, Mom?”

Not now, daughter of mine–I’m onto something here! “Well Mom, it’s sort of a math problem. We’re supposed to figure out the theorem…” Not now, girl. Build, child! BUILD!

We counted, we stacked, we built the largest possible cube using under 100 sugar cube…er…blocks. And just as we took the final tally, it hit me like a ton of bricks. The lights came on, Heaven shined down, and angels sang the Hallelujah Chorus. From a dusty crevice of my memory boomed my old math teacher’s voice:

**“Length x Width x Height = Volume” **

Which, of course, meant nothing to me. We had none of those things.

But we built it, doggone it, so we *got the answer!* In spite of not knowing how! In your face, 8th Grade Math problem, IN YOUR FACE!

Now then. You think I’m going to give you the answer, don’t you. After squatting on aching knees digging out 100 Legos of the correct size? Counting, stacking and recounting again? I think not–you’ll have to earn it. Earn it, I say! So here’s the problem again. Do you know what the answer is?

**If you had 100 sugar cubes, how many would it take to build the largest cube possible out of them?**

Do tell!

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on September 3, 2008 at 8:51 pm |Seth Rene Neonits a cube rite?

what makes the volume formula special as opposed to the generic rectangular solid formula is the fact that every side of a cube has the same measure.

so we go from L x W x H = V

to Side x Side x Side = V or simply S x S x S = V

and simplifing more we get S^3 = V

now we have to plug in 100 for V and solve for V

we get S^3 = 100

now the opposite opperation for (^3) is cuberoot which can be written as ^(1/3)

so now we get S = 100^(1/3)

if you go to a calculator, S = 4.64…

now this problem kinda makes the assumption that you cant cut up a sugar cube in half, and you DEFFINATELY cant use more that 100 cubes

so we round down to S = 4

now we can go back into the original formula and subsitute

4 x 4 x 4 = 4^3 = 64

thusly.

the largest cube you can make with 100 sugar cubes is a 4x4x4 sided cube

on September 3, 2008 at 8:56 pm |Seth Rene Neonas for the universal formula, say for when you need to find the largest cube you can make with 130560234857 sugar cubes would be as follow

take the cube root of the given volume and round down to the nearest whole number

( V^(1/3) )rounddown

on September 3, 2008 at 9:02 pm |zenofind an integer which cubed is less than 100

4x4x4=64 is the answer because 5x5x5 is 125

on September 3, 2008 at 9:03 pm |zenofind an integer which cubed is less than 100 4x4x4=64 is the answer because 5x5x5 is 125

on September 3, 2008 at 9:09 pm |K. TrainorStop, stop–you’re scaring me! lolololol!

I actually did figure out the formula the way Zeno did–but only after the visual hit me.

Thanks for stopping by! 😀

on September 4, 2008 at 6:39 am |AmyMayOK after reading Seth’s response my brain hurts and I still don’t get it.

This from the woman who bought “Algebra For Dummies” last year remember? LOL

Glad you figured it out, no matter how you did it.

on September 4, 2008 at 7:18 am |K. TrainorOh. My. Goodness.

Seth, I re-read your answer after a good night’s sleep, and I can actually follow it! Will I remember it 4 years from now when our youngest is in 8th grade? Probably not. I’m afraid you’ll just have to come back and bail me out again. But for now–this minute on THIS day…I get it. WooooHooooo!

AmyMay, I understand completely. I read that about 6 times yesterday and it lost me every time. Guess it needs time to simmer. lol!

on September 4, 2008 at 10:38 am |MJ😀 Hilarious. That’s how I felt when I went to take the GMAT to get into my MBA program. They had some math on there, but I hadn’t had an actual math class since sophomore year of undergrad. I had to study for weeks to get back in the groove!

Love your new layout 🙂

on September 4, 2008 at 10:53 am |K. TrainorGroove on, MJ, groove on. 😀

Glad you like the layout. I’m not thrilled with it, m’self, but I could not stand the Center Justify of the old one for one more second.

on September 4, 2008 at 12:58 pm |Just a MomDo you want the answer before or after I throw all of the sugar cubes across the room!

When faced with a 4th grade science question last week I told my daughter that she needed to figure it out on her own. I told her if she got it wrong it would make her remember it better. I thought this was a great cop out!

on September 4, 2008 at 3:25 pm |K. TrainorI’m very sorry Just a Mom, but as the Mommy, you KNOW you can’t throw the sugar cubes. Otherwise, you have to pick them up!

on September 4, 2008 at 5:58 pm |carolleoh good golly.

please lord help my kids to keep up the good math grades. amen.

on September 5, 2008 at 6:28 am |kweenmamaMy kids don’t even bother to ask me for help with their math anymore. I can figure it out, it just takes me longer than they have patience for so they either go to their step dad or call their father. Fine by me! I’ve never liked math.

Did you give yourself a reward for figuring it out? You should! 🙂

on September 5, 2008 at 10:54 am |SherriOur problem was – I could figure it out just not the way they needed to show it. “New Math” Glad that phase is over! Good Luck in the future!

on September 8, 2008 at 4:00 pm |colbymarshallUm…can I simplify this by just EATING the sugar cubes?

on September 9, 2008 at 1:22 pm |Sarahouch.

My head hurts.

This is why i am an English Major

on September 24, 2008 at 11:08 am |K. TrainorNo reward Kweenmama, but I’m thinking Colby’s onto something with eating the sugar cubes. 🙂

*hands Sarah two ibuprophen and a glass of cool water.