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Math Help - Best and fastest division method?

  1. #1
    Junior Member Subliminalmessage's Avatar
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    Best and fastest division method?

    So I know of two different division methods, short and long. So my question is, I've got to work out questions quickly for a numeracy psychometric test coming up.

    I will be dividing; decimals with whole numbers and percentages and fractions

    Now the test I believe will be 16 minutes long and multiple choice, so I presume none of the questions will require long division but that is just a educated (obvious) guess. Now I know the long division method as shown in this video below, takes far to long for me to realistically answer any division sums in a short amount of time, I don't want to spend too much time on one question.



    Baring in mind that it will be multiple choice, would I therefore be best just sticking with the division method below and when it doesn't come up with the exact answer just take some of the answer to choose one of the multiple choice answers?



    Now I've got one problem, I was on Youtube looking up how to divide decimals by whole numbers and one of the questions the uploader shown was.

    A) Ms. Spencer buys her class a set of 4 travel games for $39.60. What is the cost per game?

    I tried using the short division on this question and did not get exact answer or a finished answer.

    $39.60/4 - 4 goes into 39 9 times remainder 1 so I put the 1 on top of the 6. 4 goes into 16 4 times exactly = $9.4, however the answer is 9.9 or $9.90 so that is an example where the short division method annoyingly does not work.

    PLEASE HELP, just give me some advice on the question, it will be extremely appreciated, thank you.
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    Re: Best and fastest division method?

    If it's multiple choice, why not multiply each possibility by the number you are dividing by and see which one works? This could work if your numbers aren't very big. Otherwise, the short division algorithm is the quickest, unless you are good with fractions and cancelling common factors.

    I think you'll find that 4 goes into 39 9 times with a remainder of 3...
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  3. #3
    Junior Member Subliminalmessage's Avatar
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    Re: Best and fastest division method?

    Quote Originally Posted by Prove It View Post
    If it's multiple choice, why not multiply each possibility by the number you are dividing by and see which one works? This could work if your numbers aren't very big. Otherwise, the short division algorithm is the quickest, unless you are good with fractions and cancelling common factors.

    I think you'll find that 4 goes into 39 9 times with a remainder of 3...
    Oh my gosh, your right, ha ha I sometimes make those mistakes, thanks for reminding me, well at least I know that works. Oh and yes your technique is great! I mean the downside to doing this is that there's going to be 4 or 5 multiple choice answers making it painful if it's the 4th or 5th one.

    I've got another question on divisions, please help me on these.

    243/9 - 9 goes into 24, 2 times 5R, 9 goes into 53, 5 times R8, so I put decimal point down and 9 goes into 80, 8 times, 8 remainder and it goes on .8888 afterwards. So I thought the answer would be 25.8 but the answer turns out is 27, what did I do wrong or what didn't I do? (JUST DID THAT QUESTION AND GOT 73 BY ACCIDENT INSTEAD OF THE ACTUAL 63, I GOT 27 IN THE END BUT SAY FOR INSTANCE THAT HAPPENED ON ANOTHER QUESTION, WHAT WOULD I DO? THANKS.)

    and

    702/26 - 26 goes into 70, 2 times R18, 26 goes into 182 how many times? What is the quickest way to work out divisions that end up with you could say two divisions in one, so fastest way to work out how many times 26 goes into 182 in that situation? Would I be right in saying, just do 26 x 5 and then add 26s until you get the right answer or if your lucky get it first time on the x 5?

    THANKS a lot for last response.
    Last edited by Subliminalmessage; July 16th 2012 at 08:45 AM.
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    Re: Best and fastest division method?

    Quote Originally Posted by Subliminalmessage View Post
    Oh my gosh, your right, ha ha I sometimes make those mistakes, thanks for reminding me, well at least I know that works. Oh and yes your technique is great! I mean the downside to doing this is that there's going to be 4 or 5 multiple choice answers making it painful if it's the 4th or 5th one.

    I've got another question on divisions, please help me on these.

    243/9 - 9 goes into 24, 2 times 5R, 9 goes into 53, 5 times R8, so I put decimal point down and 9 goes into 80, 8 times, 8 remainder and it goes on .8888 afterwards. So I thought the answer would be 25.8 but the answer turns out is 27, what did I do wrong or what didn't I do? (JUST DID THAT QUESTION AND GOT 73 BY ACCIDENT INSTEAD OF THE ACTUAL 63, I GOT 27 IN THE END BUT SAY FOR INSTANCE THAT HAPPENED ON ANOTHER QUESTION, WHAT WOULD I DO? THANKS.)

    and

    702/26 - 26 goes into 70, 2 times R18, 26 goes into 182 how many times? What is the quickest way to work out divisions that end up with you could say two divisions in one, so fastest way to work out how many times 26 goes into 182 in that situation? Would I be right in saying, just do 26 x 5 and then add 26s until you get the right answer or if your lucky get it first time on the x 5?

    THANKS a lot for last response.
    Last time I checked, 2 x 9 = 18, so that would mean 9 goes into 24 twice with a remainder of 6...

    Also, like I said, it's easiest to perform simpler divisions after cancelling common factors. So \displaystyle \begin{align*} \frac{182}{26} = \frac{91}{13} \end{align*} after cancelling (dividing both by) 2. Then it's easier to see that 7 x 13 = 91.
    Thanks from terone71
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