
30 second arithmetic challenge - 317070
http://christianp.github.io/30secondchallenge/
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cperciva
I was doing fine until I got to "multiply by itself twice". Is that "x := x *
x * x", or "x := x * x; x := x * x"?

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Jake232
This caught me out too.

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xtrumanx
This reminds me of morning routine back in grade school called "Mad Minute"
where we would be given a sheet containing 30 or 50 simple equations to solve.
You'd have to complete it in a minute and the teacher would stopped grading at
the first wrong answer so getting the first one wrong follwed by 49 correct
answer would net you a score of zero.

When I first transferred to that school I was terrible at it but I did get
pretty good at it later on. I think it did a lot for my arithmetic skills.

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BienTek
I _hated_ "Mad Minute." I felt I had to do perfectly on it, since some other
kids did - and that was the standard the teacher set.

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clickok
Another fun game you can play in traffic[0] is to factor the license plates of
the cars ahead of you.

Weirdly, I found that doing this sort of practice made me better at abstract
mathematics. I used to think that Gauss, Euler and von Neumann being excellent
mental calculators was a side effect of their talent, but I wonder now if this
sort of practice actually amplified it instead.

\---

0\. In your car-- on foot it's surprisingly dangerous.

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effie
That's surprising. Mathematicians generally are not very good at calculations
and it always seemed to me that doing calculations fast is quite different
from mathematicians do and need.

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Someone
Back in the time of Gauss, mathematicians needed logarithm tables, and the
only ones they trusted making them where mathematicians. So, mathematicians
computed logarithms 'in their spare time'

For example, Gauss actually spent time to write a review of a table of
logarithms
([http://articles.adsabs.harvard.edu//full/1851AN.....32..181G...](http://articles.adsabs.harvard.edu//full/1851AN.....32..181G/0000095.000.html)).

He also had to compute prime numbers so that he could study their properties.
([http://science.larouchepac.com/gauss/ceres/InterimII/Arithme...](http://science.larouchepac.com/gauss/ceres/InterimII/Arithmetic/Primes/Primes.html)
claims he extended a table listing all primes up to 10,009 but never got as
far as a million, but he must have spent lots of time on calculations we now
call mundane

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rhnvrm
I wrote a small script to solve the easy ones in the browser:
[https://github.com/rhnvrm/30s_challenge](https://github.com/rhnvrm/30s_challenge)

Here is the script for solver:
[https://github.com/rhnvrm/30s_challenge/blob/master/solver.j...](https://github.com/rhnvrm/30s_challenge/blob/master/solver.js)

and here is the cheat:
[https://github.com/rhnvrm/30s_challenge/blob/master/cheat.js](https://github.com/rhnvrm/30s_challenge/blob/master/cheat.js)

Also, I found that since the methods of the game and challenge class are
public, you can actually just call it's functions. I also found a useful
resource for learning OOPs in js
[http://phrogz.net/js/classes/OOPinJS.html](http://phrogz.net/js/classes/OOPinJS.html)
and how to make methods private. There is another cool article here on how to
make members private and protected here
[http://philipwalton.com/articles/implementing-private-and-
pr...](http://philipwalton.com/articles/implementing-private-and-protected-
members-in-javascript/)

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dmourati
This makes me realize my long multiplication above 100 really sucks.

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DDR0
Jeez, I got to like operation 3. That said, I am surrounded by beer cans,
so... yeah, don't drink and derive.

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Tinyyy
I think hard is bugged? It is around easy's difficulty and much easier than
medium.

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MaulingMonkey
Medium and hard throw in new kinds of operations, but how hard a problem is
for me at least seems to mostly scale with the number of digits I have to
juggle, not the operation "complexity".

E.g. if I'm at 14, an "easy" multiply "by itself" forces me to multiply long-
form (I don't even have 4 x 14 in my mental LUT... so 140 + "uh... 56
plus..."). On the other hand, again starting at 14, a "hard" multiply by 4/7
instead is trivially 8 (mentally rewriting to (14/7)*4)

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CoryG89
This reminds me of a math game we used to play in elementary school called 24.
I also recreated it, uses websockets for multiplayer:

[https://get24.jit.su](https://get24.jit.su)

~~~
minaguib
Please allow easy editing of previous wrong guess

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bradb3030
Really fun, nice game!

4/6 easy, 19.1s 47/77 medium, 16.2s 19/25 hard, 17.8s

I started scribbling numbers on paper without looking down when I got to the
hard ones, which helped...but I still think the hard ones were slightly easier
than medium ones.

Good question design: forcing you to look ahead simplify things like 69 * 2 -
5 / 7 ...

realizing that 69 is one smaller away from being evenly divisible by 7, when
doubled is 2 smaller, minus 5 makes it 7 smaller so the divided by 7 can apply
to the thing it's close to...140 as well as the 7 smaller..140/7 minus 1...19

Common core on steroids?

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pronoiac
Please make / and + more distinct!

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kyberias
Yes, it's hard to see the difference.

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kip_diskin
This is the most infuriating thing I've played since QWOP

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ilanco
Didn't know that one, lucky it's saturday

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temo4ka
Looks like a place to practice mental arithmetic tricks, you know, like
multiplication by 11:

    
    
      11 × 16 = 1(1+6)6
      34 × 11 = 3(3+4)4
      124 × 11 = 1(1+2)(2+4)4
    

Or multiplication table 10 through 20:

    
    
      14 × 17 = (14+7) × 10 + 7 × 4
      13 × 18 = (13+8) × 10 + 8 × 3

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ForHackernews
I don't understand how this works. Are you supposed to enter the answers as
you go? Or just the final answer? I tried entering intermediate values and got
zero feedback from the interface.

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smorrow
The trick seems to be to avoid subvocalising (where possible).

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monochromatic
Why does that help?

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FoeNyx
supposedly subvocalising is slowing you (resources allocated to your TTS
module rather than to your arithmetic coprocessor ;)

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kip_diskin
This is the most infuriating thing I've played since qwop

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deanclatworthy
This is a rather fun little exercise. Would be good to use in a classroom,
although I found it a little hard going from left to right on a laptop screen

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adsche
Small bug: When you did not solve it in time and the answer is diplayed,
clicking on the timer will add it to the solved count.

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buffoon
11 ... ok

+5 ... easy

x itself ... ugh. more coffee.

divide by 7 ... TI83 slides out of desk drawer

Actually it's really fun - thanks :)

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Roadgazer
Fun, reminds me my school classroom exercise in elementary

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Nickersf
Got an A in calc II but this gets the better of me? GRRR!

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gaelow
It's arithmetic, not calculus. In both your performance depends on three
factors: technique, practice, capacity. I don't know about capacity, but
practising and learning calculus techniques is not the same as practising and
learning arithmetic techniques. In fact if you wan't to get good at calculus
it is probably counter-productive and inneficient to waste time on solving
arithmetic operations "by hand" when using a calculator will be much faster
and help you keep focused on the calculus problem at hand.

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illivah
This is amazing, and I need to work on my arithmetic.

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gansai
Its like kind of frappy bird game, some may get addicted, not to lose...

