Random integers

[John T]

I'm trying to create pairs of random integers that ALWAYS add up
correctly. Sometimes due to the rounding up process I get an error
of 1 when added together.

If you are kind enough to reply by email using "reply to" take out
"the rubbish" from my address.

Cheers
John T

 

[Guest]

And just what does "correctly" mean when you're at home?

 

[John T]

On Thu, 18 Mar 2004 12:50:58 -0800,


Example: I want 19 + 13 to equal 32, not 31 or 33 !
Unfortunately working in the education tends to restrict creative
interpretations and stiffle surreal debate!

 

[Frank Kabel]

Hi john
this would add up correctly. Question: do you have these problem then
using mathematical calculations like divisision, etc. or can you post
an example of your data and the formula you used which results in a
wrong result

 

[John T]

On Thu, 18 Mar 2004 22:52:13 +0100, "Frank Kabel"
Just addition & subtraction at the moment.

I'm preparing files for teachers to use on a data projector to rapid
recall of number bonds.
I've put two data cells (B3 & D3) onto a sheet called "setup" to allow
the teacher to set the range of random numbers generated.

On the "quiz" spreadsheet I've used
=RAND( ) *( setup!B3-1)+1 and =RAND( ) *( setup!D3-1)+1 to
generate 2 random numbers to be added.
I have a cell that adds the two numbers together, along with a macro
which hides the answer setting font & background to the same colour
until a second macro button is pressed to reveal the answer.

Sadly the answer can be 1 out due to the way random numbers are
created as decimals.

Cheers

John Taylor
Staffordshire
UK

 

[Frank Kabel]

Hi
have a look at the function
RANDBETWEEN. e.g.
=RANDBETWEEN(setup!B3,setup!D3)

 

[John T]

On Thu, 18 Mar 2004 23:30:27 +0100, "Frank Kabel"


Hi, thanks again for your suggestion, sadly it produces ######## in
the cell.

Could I be very cheeky and forward you the file - it's 86 kb / It
would make it easier for you to se what I'm trying to do.

Regards

John

 

[Frank Kabel]

Hi
you can email me your sheet but before try changing the order of your
parameters to
=RANDBETWEEN(setup!D3,setup!B3)
RANDBETWEEN(upper,lower)

 

[AlfD]

John:

I don't think you have a random number problem: I think the issue i
rounding.

Have a look at, for example, TRUNC(x) which returns the number x wit
its decimal part chopped off (not formatted, rounded or whatever, bu
amputated). Its behaviour will therefore be predictable.

Alternatively, have a look at INT which returns the bit before th
decimal point.

Al