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Generating (in a random order)each number once from a given number

  1. #1
    Neil Goldwasser
    Guest

    Generating (in a random order)each number once from a given number

    I am trying to make a self-marking interactive times table test for my
    students.

    The aim is that they can choose the times table by entering a number into
    one cell, and Excel will generate a set of questions to match. These need to
    be in a random order so as to test rote memory rather than the sequence of
    that times table. So

    7 x 3
    11 x 3 etc...
    rather than
    1 x 3
    2 x 3 etc...

    I have made my sheet, and I just need to rejig it so that the first number
    in the above calculations is 1) randomly generated and 2) is only generated
    once (I want them to test up to 12 x ..., doing each question once only (so
    do not want, for example 2 x 3 coming up twice as this would mean the second
    one takes up the place of the question that will be "missing").

    So I need the first cell e.g. A1 to randomly generate (with fair
    probability) a number from the set {1,2,3,4,5,6,7,8,9,10,11,12} so that the
    line will form e.g. 7 x 3.

    The second cell A2 can't duplicate, so would need to pick randomly from the
    set {1,2,3,4,5,6,8,9,10,11,12} - so that it now cannot pick the number 7 that
    has already come up.

    And so on and so on until the last cell A12 can only pick the last remaining
    number that has not already been generated.

    Ideally, I would like the numbers to then remain fixed so that the sheet can
    mark what they have done as right or wrong, and only generate a new set of 12
    questions once a button is pressed, or a different value is entered somewhere
    or whatever (as long as they choose when it "recalculates" and Excel doesn't
    do it every time they enter an answer).

    Does anybody have a solution for this teacher who is desperately trying to
    do what he can for his students? I'd be really grateful!

    Thanks to everyone in advance, Neil Goldwasser

  2. #2
    Peo Sjoblom
    Guest

    Re: Generating (in a random order)each number once from a given number

    Put 1 in D1, 2 in D2 and copy down to D11, that will give you
    1
    2
    3
    4
    etc

    in E1 put

    =RAND()

    copy down to E11

    Now if you don't want these numbers to change every time you calculate
    the sheet, select and copy (edit>copy or ctrl + C) E1:E11, while still
    selected do edit>paste special and select values, now in A1 put

    =INDEX($D$1:$D$11,RANK(E1,$E$1:$E$11))

    copy down to A11

    if you don't copy and paste special the RAND() values will change each time
    the sheet is calculated thus the values in A1:A11 will change as well but if
    you copy the RAND range and paste special as values it will be fixed


    --

    Regards,

    Peo Sjoblom

    "Neil Goldwasser" <[email protected]> wrote in
    message news:[email protected]...
    > I am trying to make a self-marking interactive times table test for my
    > students.
    >
    > The aim is that they can choose the times table by entering a number into
    > one cell, and Excel will generate a set of questions to match. These need

    to
    > be in a random order so as to test rote memory rather than the sequence of
    > that times table. So
    >
    > 7 x 3
    > 11 x 3 etc...
    > rather than
    > 1 x 3
    > 2 x 3 etc...
    >
    > I have made my sheet, and I just need to rejig it so that the first number
    > in the above calculations is 1) randomly generated and 2) is only

    generated
    > once (I want them to test up to 12 x ..., doing each question once only

    (so
    > do not want, for example 2 x 3 coming up twice as this would mean the

    second
    > one takes up the place of the question that will be "missing").
    >
    > So I need the first cell e.g. A1 to randomly generate (with fair
    > probability) a number from the set {1,2,3,4,5,6,7,8,9,10,11,12} so that

    the
    > line will form e.g. 7 x 3.
    >
    > The second cell A2 can't duplicate, so would need to pick randomly from

    the
    > set {1,2,3,4,5,6,8,9,10,11,12} - so that it now cannot pick the number 7

    that
    > has already come up.
    >
    > And so on and so on until the last cell A12 can only pick the last

    remaining
    > number that has not already been generated.
    >
    > Ideally, I would like the numbers to then remain fixed so that the sheet

    can
    > mark what they have done as right or wrong, and only generate a new set of

    12
    > questions once a button is pressed, or a different value is entered

    somewhere
    > or whatever (as long as they choose when it "recalculates" and Excel

    doesn't
    > do it every time they enter an answer).
    >
    > Does anybody have a solution for this teacher who is desperately trying to
    > do what he can for his students? I'd be really grateful!
    >
    > Thanks to everyone in advance, Neil Goldwasser




  3. #3
    Neil Goldwasser
    Guest

    Re: Generating (in a random order)each number once from a given nu

    That's great! Thanks Peo, it has really helped.

    Just one quick question though:
    Is there a way of re-generating the numbers again on request, e.g. with a
    button or something, so that once the students had completed the first set of
    12 questions, they could get the same times table questions, but in a
    different order?

    If it is possible to have a non-macro way of recalculating the formulae
    manually (i.e. when they choose to generate a new set of questions rather
    than the random function happening every time a new cell value is given) then
    this would be best, but if it has to be a macro then I have picked up some
    knowledge of these (thank you again to Norman Jones for kick-starting my
    education in this area, just in case you are reading this!).

    Also, is it possible to clear cells to give blank cells when I enter a
    particular value somewhere or press a button etc...? Ideally I'd like the
    students to complete the first set of 12 times table question, press button A
    to clear their answer cells, press button B to generate the questions in a
    new random order, and then answer them all over again.

    I apologise in advance if this sounds like I'm being picky but these
    students will really benefit from practising each times table several times
    over, and if they practised the same random order over and over again the
    danger is that they'll learn an incorrect number sequence (e.g. thinking that
    in the three times table 21 will always follow 6 or something horrendously
    misleading like that). I work in Learning Support so I have to make sure to
    avoid such pitfalls.

    Again, thanks for your help so far, Neil


    "Peo Sjoblom" wrote:

    > Put 1 in D1, 2 in D2 and copy down to D11, that will give you
    > 1
    > 2
    > 3
    > 4
    > etc
    >
    > in E1 put
    >
    > =RAND()
    >
    > copy down to E11
    >
    > Now if you don't want these numbers to change every time you calculate
    > the sheet, select and copy (edit>copy or ctrl + C) E1:E11, while still
    > selected do edit>paste special and select values, now in A1 put
    >
    > =INDEX($D$1:$D$11,RANK(E1,$E$1:$E$11))
    >
    > copy down to A11
    >
    > if you don't copy and paste special the RAND() values will change each time
    > the sheet is calculated thus the values in A1:A11 will change as well but if
    > you copy the RAND range and paste special as values it will be fixed
    >
    >
    > --
    >
    > Regards,
    >
    > Peo Sjoblom
    >
    > "Neil Goldwasser" <[email protected]> wrote in
    > message news:[email protected]...
    > > I am trying to make a self-marking interactive times table test for my
    > > students.
    > >
    > > The aim is that they can choose the times table by entering a number into
    > > one cell, and Excel will generate a set of questions to match. These need

    > to
    > > be in a random order so as to test rote memory rather than the sequence of
    > > that times table. So
    > >
    > > 7 x 3
    > > 11 x 3 etc...
    > > rather than
    > > 1 x 3
    > > 2 x 3 etc...
    > >
    > > I have made my sheet, and I just need to rejig it so that the first number
    > > in the above calculations is 1) randomly generated and 2) is only

    > generated
    > > once (I want them to test up to 12 x ..., doing each question once only

    > (so
    > > do not want, for example 2 x 3 coming up twice as this would mean the

    > second
    > > one takes up the place of the question that will be "missing").
    > >
    > > So I need the first cell e.g. A1 to randomly generate (with fair
    > > probability) a number from the set {1,2,3,4,5,6,7,8,9,10,11,12} so that

    > the
    > > line will form e.g. 7 x 3.
    > >
    > > The second cell A2 can't duplicate, so would need to pick randomly from

    > the
    > > set {1,2,3,4,5,6,8,9,10,11,12} - so that it now cannot pick the number 7

    > that
    > > has already come up.
    > >
    > > And so on and so on until the last cell A12 can only pick the last

    > remaining
    > > number that has not already been generated.
    > >
    > > Ideally, I would like the numbers to then remain fixed so that the sheet

    > can
    > > mark what they have done as right or wrong, and only generate a new set of

    > 12
    > > questions once a button is pressed, or a different value is entered

    > somewhere
    > > or whatever (as long as they choose when it "recalculates" and Excel

    > doesn't
    > > do it every time they enter an answer).
    > >
    > > Does anybody have a solution for this teacher who is desperately trying to
    > > do what he can for his students? I'd be really grateful!
    > >
    > > Thanks to everyone in advance, Neil Goldwasser

    >
    >
    >


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