Little Math help? (Easy problem)

[Jester]

1 3/5 + 7/8 divided by 1/3

They really should have parentheses to tell you what to do first.

If we do the addition first:

1 3/5 + 7/8 divided by 1/3
1 24/40 + 35/40 divided by 1/3 (converting fractions to make denominators match)
1 59/40 divided by 1/3 (adding fractions)
2 19/40 divided by 1/3 (converting fraction to nearest whole number)
2 19/40 times 3/1 (recognizing that dividing by a fraction is the same as multiplying by that fraction flipped)
2 19/40 times 3 (converting fraction to nearest whole number)
6 57/40 (multiplying)
7 17/40 (converting fraction to nearest whole number)

If we do the division first:

1 3/5 + 7/8 divided by 1/3
1 3/5 + 7/8 times 3/1 (recognizing that dividing by a fraction is the same as multiplying by that fraction flipped)
1 3/5 + 7/8 times 3 (converting fraction to nearest whole number)
1 3/5 + 21/8 (multiplying)
1 3/5 + 2 5/8 (converting fraction to nearest whole number)
1 24/40 + 2 25/40 (converting fractions to make denominators match)
3 49/40 (adding)
4 9/40 (converting fraction to nearest whole number)

So to get the correct answer according to the book, you must do the division first.

Now, one thing that is important to note is that while the problem as stated LOOKS to most people like you should add first then divide, the general rule in math when there are no parentheses present is that you do multiplication/division first and addition/subtraction afterwards. Which seems counterintuitive to the way the problem is stated, I know. But that IS the math rule.

(Of course, when there ARE parentheses, you always do the computations within the parentheses first, before doing the computations outside of them.)

Yes, I was kind of a math whiz in school. Why do you ask?

[r2cagle]

Well Plaid... at least you now know who to ask for extra tutoring......LOL

[Jester]

Bullshit. Tutoring should be done in person. I recommend that the Plaidster get a cute little chica to tutor him. Preferably a "hands on" tutor.

One stone. Two birds. 'Nuff said.

[Cazzi]

Easy problem?
Even with the explanations its still went right over my head
I can do the add/subtract/divide bit & 8 bit binary calculations but algebra etc just never sank in

[Jester]

Easy problem?
Even with the explanations its still went right over my head.

Really? I tried to make my explanations as simple as possible, and went step by step.

I know not everyone gets math the way I do. Hell, at work when making change, unless I am really tired, really hungover, or really tired and hungover, I always instantly know the change needed when someone pays their bill. It's sometimes a little disturbing to me how quickly I do math in my head, actually.

But because not everyone gets it like I do, when I explain it, I try to explain it as simplistically as possible.

Then again, it might be like someone else explaining finances to me. As good as I am at math, both taxes and finances make zero sense to me. I have an accountant because all that tax shit is complete Greek to me. Hell, I would have an easier time understanding actual Greek* than I would understanding taxes. Ditto finances, and I mean as a business, not personal finances. My buddy His Majesty is in the financial world, as is my cousin The Banker, and when His Majesty starts talking about his job, my eyes glaze over and roll to the back of my head, and I haven't the foggiest fucking clue what he's talking about.

Sound familiar?



*Now I'm hungry for Greek food!

[Cazzi]

Sound familiar?

Actually, I think its great... coz it wouldn't half be boring if we all thought the same & knew the same stuff We'd have nothing new to talk about or learn.

My big maths problem came from school. I went to an old fashioned girls grammar school... the type they sent the <Ahem> brainy (allegedly) kids; those who passed the good old 11+ exam of whom three others besides me did at my primary school did; or kids who came from families with money. When it came to maths/English I was "told" what set & type of thing I was going to be studying, rather than being allowed to decide for myself.

For some reason the PTB put myself and another girl in the bottom math set where we didn't really touch much on algebra, I think the most complicated thing we did was look up sines & cosines in a table! Our teacher wasn't much pleased, she thought we should have been in a higher group, but at the time all she could do was keep giving us extra work to keep up occupied as most of her time as taken up with the less able students.

But on the plus side with all that, I learned how to do basic math without a calculator, can do addition, subtraction, multiplication etc in my head, and on starting college along with another girl from the school, the pair of us finished & got the highest marks in a basic math test that those who came from more modern, progressive schools couldn't manage without calculators

I think the fact I finished the exams for that subject just losing one mark for untidy writing says that the PTB got it wrong slightly

I have been toying with the idea of taking an introductory level uni maths course while I'm slowly trying to get my degree, but keep chickening out.. hmm come to think of it, there may even be a full set of papers & text lying around from when my ex did one years ago, i seem to remember keeping them in case they helped my kids with their school work

[AdminAssistant]

I use a calculator for simple addition and subtraction. As soon as I saw fractions, I was like, "Yeah, I'm not even gonna touch that." I'll just stay over here with my literature, tyvm.

[Chromatix]

Fractions are easy to do on the computer, provided you don't mind converting both the problem and the answer to decimal. "A B/C" is simply A + (B ÷ C).

With that rule in effect, and remembering that "stronger" operations are done before "weaker" ones in case of ambiguity:

1 3/5 + 7/8 ÷ 1/3

...becomes 1.6 + 0.875 ÷ 0.3333333333... (is it bad that I can do that conversion in my head?)

...which is also 1.6 + (0.875 * 3), or 1.6 + 2.625 = 4.225. Which is the same as 4 9/40.

[ArcticChicken]

(is it bad that I can do that conversion in my head?)

1/3? No. 7/8? Yes.

My problem is that while it's easy to convert fractions into decimals, I cannot convert decimals into fractions. I know a few, but they're the easy ones.

[Chromatix]

Just to check if you're doing the sum in the right order, you don't need to. Just convert the answer into decimal.

But there's a trick to doing it the other way, too. Treat it as 225/1000, and normalise it:

225/1000, cancel 5s = 45/200, cancel 5s again = 9/40.

[Becks]

It's too early for math.

[Plaidman]

Another embrassing request.

Can anyone send me the formuals for multplactions and division on decimals?

I thought I knew the formual, but again, it's not matching the answers.

I could have sworn something like, example


6.42 X 4.33 Would be

Smaller on top so

4.33 TIMES
6.42 (Not that it matters, just something my 2nd grade teacher told me)

Would be

---866
-1332
2598

Would then eqauls
273986

Then put the dot and equal number of spaces to the left of last number equal to the above numbers, so it would be four spaces, so the answer should be

27.3986

Doubt it's right. None of what I've done is right.

Division I've completly forgotten.

Sorry. I'm feeling really dumb right now that I've forgotten it all. I use to be decent at math, and now I've completly fogotten how to do any of it.

[ArcticChicken]

Multiplying and dividing decimals is just like multiplying and dividing whole numbers.

You wind up with as many places after the decimal point as there are in all the numbers you're using combined.

So if you're multiplying 6.3 X 7.25 = 45.675

In 6.3 there is one place after the decimal, and in 7.25 there are two places after the decimal. In the answer, 45.675, there are three places after the decimal.

I can't tell you how to do it in long division, because I can't do long division to save my life, luckily all my math classes have let me use a calculator.


In the problem you mentioned, you just did the math wrong.

I prefer to put the bigger number on top, so....


--6.42
--4.33
_______
--1926
-19260
256800
_______
27.7986

[ParkingWitch]

6.42 X 4.33 Would be

Smaller on top so

4.33 TIMES
6.42 (Not that it matters, just something my 2nd grade teacher told me)

Would be

---866
-1332
2598

Would then eqauls
273986

OK I see where this went funny. Just didn't carry the one from the multiples.
The +1 shows where I am carrying the tens place from the previous x.

-- 4.33
- x6.42
---------

---- 866 = 3x2 =6 3x2=6 4x2=8
--1732 = 4x3 =12 carry the 1 to 4x3 is 12+1 = 13 carry the one to 4x4 is 16+1=17
-2598 = 6x3 =18 carry the1 =6x3 is 18 +1 =19 carry the one 6x4 is 24 +1=25

-------
277986 and when you add the decimal in you get

27.7986


Bleech I always hated having to do carried numbers.

[Chromatix]

Division is fun too. But just like with multiplication, you can throw away the decimal point to get the digits, and then the main trick is working out where to put it afterwards.

A useful thing to remember is that division is just like fractions. That means that you can multiply both the numerator and denominator by the same amount, and the quotient (the answer) will remain the same. Moving the decimal point is the same as multiplying or dividing by 10. Therefore, if you move the decimal point to the right by the same amount on both, it won't affect the answer. You can add zeroes if you run out of digits, too.

Finally, you can make a decimal answer by simply continuing the division process instead of writing down a remainder. Don't go crazy about that though, as usually you only need a few extra digits. Once you get to the last digit, increase it by one if the remainder after that is at least half the denominator.