## Re: Decoy Numbers for Squareroot

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• Does some one know whether according to rules of mental calculation world cup and memoriad competition, solution of sqrt(685632) which is 828.02898499992 will
Message 1 of 12 , Jul 1 1:10 PM
Does some one know whether according to rules of mental calculation world cup and memoriad competition, solution of sqrt(685632) which is 828.02898499992 will be rounded to 828.02899 or 828.02898.
What if actual sqrt were 828.0289850001 or so. Will MCWC accept both solutions as correct?
Thanks,
Amit

--- In MentalCalculation@yahoogroups.com, "SelÃ§uk Soner AkgÃ¼l" <ssakgul@...> wrote:
>
> I'll look to your message including that algorithm after writing this
> message.
>
> My calculator says that sqrt 685632 = 828.02898499992...
>
> I don't know or understand the rounding rule. Can we round that number first
> to 828,028985 and then 828,02899? I didn't check other answers yet. But they
> are very similar; ###.#####499...
>
>
> [Non-text portions of this message have been removed]
>
• I don t what rules MMWC uses but I learned rounding from my mother, a high school math teacher. You round the digit to the left up one if the digit to the
Message 2 of 12 , Jul 2 10:31 AM
I don't what rules MMWC uses but I learned rounding from my mother, a high school math teacher. You round the digit to the left up one if the digit to the right is five or bigger but only if that digit is five or bigger without having been rounded up from four.

In other words, .44445 can be rounded to .4445 but not to .445,
.45 and ridiculously, .5 or ever 1 if one continues rounding.

Jerry Newport

--- In MentalCalculation@yahoogroups.com, "amitgarg78" <amitgarg78@...> wrote:
>
> Does some one know whether according to rules of mental calculation world cup and memoriad competition, solution of sqrt(685632) which is 828.02898499992 will be rounded to 828.02899 or 828.02898.
> What if actual sqrt were 828.0289850001 or so. Will MCWC accept both solutions as correct?
> Thanks,
> Amit
>
> --- In MentalCalculation@yahoogroups.com, "SelÃ§uk Soner AkgÃ¼l" <ssakgul@> wrote:
> >
> > I'll look to your message including that algorithm after writing this
> > message.
> >
> > My calculator says that sqrt 685632 = 828.02898499992...
> >
> > I don't know or understand the rounding rule. Can we round that number first
> > to 828,028985 and then 828,02899? I didn't check other answers yet. But they
> > are very similar; ###.#####499...
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
• If you use the formula given in the rules page, you get the maximum number 7 for this answer. So, this gives you 28 points in the competition. The rule: Let A
Message 3 of 12 , Jul 4 4:45 AM
If you use the formula given in the rules page, you get the maximum number 7
for this answer. So, this gives you 28 points in the competition. The rule:

Let A be the answer written down by a participant and B the exact solution.
> Then let N be the maximal integer for which |A-B|≤5·10^(2-N) holds. Then the
> number of digits regarded as being correct is N, but no more than 8 or the
> number of digits written down by the participant.

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