6th grade math question

[kimmar067]

I reject the question. No store sells things for 91% off.

....you've never heard of a fire sale?

 

[leebee]

It was 9% OFF -- 91% of the regular price


I don't know what to tell you in regards to them not having been taught division yet really?

but the answer is

(26/91)*100 = 28.57

Winner, winner, chicken dinner! OP, you just know too much math and automatically converted the 91% to a decimal! I would have done it your way, also, and spent quite a bit of time thinking about how to do this… marlynnp beat me to it!

 

[Mickey'snewestfan]

Winner, winner, chicken dinner! OP, you just know too much math and automatically converted the 91% to a decimal! I would have done it your way, also, and spent quite a bit of time thinking about how to do this… marlynnp beat me to it!

This way gives the same answer, and doesn't solve the problem which is that my kid can't divide by a two digit number.

The calculator solution is what we did, I had him set up the problem, and then let him use a calculator for the answer. But given that the problem was on a test prep sheet, where they were working towards a test that would be calculator free, and that every other problem on the sheet, and every other problem in the unit has been doable without a calcuator or a 2 digit divisor, I don't think they intended for kids to use the calculator.

I think the teacher wrote the problem wrong. I think it was either supposed to be 91% OFF or the original price was $26.

 

[kaytieeldr]

Okay, well, I used trial-and-error and multipliction:

Someone bove had tried multiplying the $26 by 1.09 (too low) and 1.11 (slightly too high). I ended up with having to multiply the discounted $26 price times 1.09885, to get a totl of 1 $28.5701, which rounds to the expected $28.57.

 

[FlightlessDuck]

Learning to divide by decimals in long hand is dumb. Calculators exist for a reason.

 

[leebee]

This way gives the same answer, and doesn't solve the problem which is that my kid can't divide by a two digit number.

Ooops, I was focusing on the 'dividing by a decimal' issue and forgot that they hadn't done double digit division yet. Actually, this is a peculiar issue, I think. I teach in special ed, and even my 5th graders are working on division with double digits. Granted, we use multiplication charts a lot, but we're working on it. Are you sure they aren't doing this and your student just doesn't understand it?

If you talk with the teacher about this problem, keep us in the loop!

 

[Mickey'snewestfan]

Ooops, I was focusing on the 'dividing by a decimal' issue and forgot that they hadn't done double digit division yet. Actually, this is a peculiar issue, I think. I teach in special ed, and even my 5th graders are working on division with double digits. Granted, we use multiplication charts a lot, but we're working on it. Are you sure they aren't doing this and your student just doesn't understand it?

If you talk with the teacher about this problem, keep us in the loop!

He can do long division with a 1 digit divisor. Such as 23,945/4, and long division with decimals in the divisor.

We're in a common core state, and the common core standards for fifth have students exploring long division using place value models, repeated subtraction, arrays and other strategies. The standard algorithm is taught in sixth.

 

[leebee]

He can do long division with a 1 digit divisor. Such as 23,945/4, and long division with decimals in the divisor.

We're in a common core state, and the common core standards for fifth have students exploring long division using place value models, repeated subtraction, arrays and other strategies. The standard algorithm is taught in sixth.

When you say long division with decimals in the divisor, I assume you mean single digit decimals? Otherwise, what's the difference between a double digit divisor and a 2-digit decimal divisor?

We are common core, too, but aren't implementing it until Fall 2014. I'm not excited about it, especially as the trainer told me that in math it's the process that counts and not the answer. Yes, I cross-questioned her and she said CC math doesn't care if you get the right answer or not, as long as you understand what should be happening. Ummm… explain that to the bank when the check bounces. SO I guess my snarky "Common Core" answer is that it doesn't matter if your student can get the right answer as long as he understands what he needs to do! :good vibes:

Seriously… good luck with this. Maybe the teacher just forgot that she hasn't taught division with double digit divisors yet? It's easy to make mistakes when making up a worksheet… BTDT!

 

[Mickey'snewestfan]

When you say long division with decimals in the divisor, I assume you mean single digit decimals? Otherwise, what's the difference between a double digit divisor and a 2-digit decimal divisor?

We are common core, too, but aren't implementing it until Fall 2014. I'm not excited about it, especially as the trainer told me that in math it's the process that counts and not the answer. Yes, I cross-questioned her and she said CC math doesn't care if you get the right answer or not, as long as you understand what should be happening. Ummm… explain that to the bank when the check bounces. SO I guess my snarky "Common Core" answer is that it doesn't matter if your student can get the right answer as long as he understands what he needs to do! :good vibes:

Seriously… good luck with this. Maybe the teacher just forgot that she hasn't taught division with double digit divisors yet? It's easy to make mistakes when making up a worksheet… BTDT!

Sorry, I meant decimals in the dividend.

The Common Core expects kids to have fluency, accuracy, and comprehension. They aren't things you choose between.

 

[SmallWorld71]

He can do long division with a 1 digit divisor. Such as 23,945/4, and long division with decimals in the divisor.

We're in a common core state, and the common core standards for fifth have students exploring long division using place value models, repeated subtraction, arrays and other strategies. The standard algorithm is taught in sixth.

FWIW - This is from the 5th grade Common Core standards:

Find whole-number quotients of whole numbers with up to four-digit dividends and two-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

IMO, this seems to say that they should have been taught division by two-digit divisors in 5th grade. We are a state that has adopted the Common Core and I know my 5th grade daughter has covered it this year. The 4th grade Common Core has only a one-digit divisor in it.

In any case, good luck with the tutoring.

 

[bdcp]

Learning to divide by decimals in long hand is dumb. Calculators exist for a reason.

Really? It's a math skill and there's nothing wrong with that. I'm 53 and can still divide with decimals with a pencil and paper. No one is learning real math anymore. Everything can be "close". Really? Math is not estimating. Estimating is something you figure out when you learn to do the math problem, not the other way around. My oldest DS (30) was a math major in college and just shakes his head at how they teach kids "math" now.

 

[Mickey'snewestfan]

FWIW - This is from the 5th grade Common Core standards:

Find whole-number quotients of whole numbers with up to four-digit dividends and two-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

IMO, this seems to say that they should have been taught division by two-digit divisors in 5th grade. We are a state that has adopted the Common Core and I know my 5th grade daughter has covered it this year. The 4th grade Common Core has only a one-digit divisor in it.

In any case, good luck with the tutoring.

And this is from the sixth:

CCSS.Math.Content.6.NS.B.2 Fluently divide multi-digit numbers using the standard algorithm.

Explaining something with the an equation (5th grade standard) and solving something with an equation (6th grade standard) are two different things.

 

[shortbun]

You lost me at 26 = .91P

Seriously, I'm going to be the most useless parent when it comes to math. English, science, history... Got that covered. BUT MATH?! No bueno.

Better bone up because kids really need help with math. I relearned up to Pre-calc while my son was taking math. Haha! He thinks I'm smart. I worked hard at it. Now that he's in Physics, I'm lost if math comes into play because I don't know what formulas to use.

 

[ErikdaRed]

Hopefully dividing by 10 is allowed.

If so,

26 = 91%
2.6 = 9.1%
.26 = .91%
.026 = .091%
.0026 = .0091%

26 + 2.6 - 0.026 - 0.0026 = 91% + 9.1% - 0.091% - 0.0091%

28.5714 = 99.9999% (or close enough for currency).

So $28.57 was the original price.