
Ten seconds of math - countryqt30
http://www.mental-math-trainer.com/
======
bvanslyke
Noticed some fun SEO hacking at the bottom of the page:

<p class="hardly-visible">puzzles calculate formula mathematics maths decimal
number calculating mathematician multiply measurement probability equation
division measure homework units word problem solve converting resources
tessellation anxiety math problem problems convert unit ratio number
trigonometry perimeter divide mental multiplication calculus math quadratic
triangle teselation problems pi change equations homeschool fraction
tesellation converter maths problems fractions conversion math prime mathmagic
Theorem calculator percent magic homework fractol volume math math tesselation
math math math mathematical statistic unit geometry math polygon square math
pre-algebra algebra word statistics games area math Pythagorean fractal
history trapezoid maths conversion circle numbers circle </p>

~~~
troels
They should remove that. It'll get them smacked by the google spam team
eventually.

~~~
ajcarpy2005
Could Google theoretically calculate the probability that some text on a
webpage is extremely hard or impossible for humans to readily see based on
info from the source page about the background and text?

~~~
scrollaway
Not just theoretically. Very concretely.

~~~
ajcarpy2005
Well I said probability because depending on how complex the background is
such as photographs, video, or some weird scrolling behavior, there could be
some hindrances to having a computer accurately or computationally-efficiently
determine this.

~~~
allendoerfer
Google uses filters, which run in different intervals apart from the main
algorithm and have different effects for a page or the whole website. This is
why spammy SEO tactics often "work for a while" \- until said computationally
intensive filter catches them and often punishes the whole website. Prominent
examples for these filters are Panda [0] and Penguin [1].

[0]:
[https://en.wikipedia.org/wiki/Google_Panda](https://en.wikipedia.org/wiki/Google_Panda)

[1]:
[https://en.wikipedia.org/wiki/Google_Penguin](https://en.wikipedia.org/wiki/Google_Penguin)

------
sillysaurus3
When I was near the end, I pressed backspace to clear my answer, and it wound
up navigating me back to HN, wiping out my results.

(I hate backspace-to-go-back. It's the worst feature in a browser. Is there a
way to turn it off?)

This mental math exercise is a cool and fun concept! Good execution.

~~~
rkwz
> I hate backspace-to-go-back. It's the worst feature in a browser. Is there a
> way to turn it off?

I _love_ this feature. Makes browser navigation keyboard friendly.

Different strokes for different folks I guess.

~~~
friendzis
What about [alt]+arrow?

------
mkoryak
I thought that maybe the ranking was real.. no its not

    
    
      function getRank(score) {
        // TODO we should add a real ranking one day
        var ONE_BARELY_REACHES_THIS_SCORE = 200;
        return Math.floor(100 * Math.min(Math.E * score / (ONE_BARELY_REACHES_THIS_SCORE * Math.PI), 1));
      }

~~~
flares
WTH?? then why release it in the first place.. That's the only crucial step in
this whole concept..

~~~
tuxone
It can't be the crucial step since one could open javascript console and type

    
    
      foo=true;$("#question-answer").bind('keydown', function(){if(foo)$("#question-answer").val(eval($("#question").html()));$("#question-answer").keyup();foo=!foo;});

~~~
flares
okay.. now so.. what is the crucial step in this whole thing?

is it generating random numbers with random operators i between them and
evaluating whether the solution given by the user is correct and count the
number of correct responses??

By crucial step i meant the logic on how he calculates the percentage of
people below.. how it changes when the operators used are changed.(is it
dependent on operators in the first place? ) and when the range is changed?
etc..

------
mtam
After going for several minutes I gave up.

In addition to a leader board, it needs to: \- Have a time limit and see who
can get the most calculations done on that fixed time \- or, have a fixed
number of calculations and see how fast people can answer them \- or, it could
get faster as you progress

The calculation of the "you are better than X%" needs to be fixed because
everybody in my office was better than 100%

~~~
johnlopez
I was thinking maybe instead of a leaderboard, graphs/analysis of raw data
would be very cool, such as accuracy and answers per second and total score,
and how those stats match up with the rest of the people who have played

------
danbruc
For me there is a set of calculations I can do without thinking and there is a
set where it takes several seconds to figure the solution out. No smooth
transition. Is it the same for you? If yes, this would make tuning this game
pretty hard because it is either to easy or to hard.

~~~
Ntrails
When I turned squares on I hit a wall at 23^2 etc. I can do it, but it's 10
seconds just to do that calc. Basically anything bigger than 14.

For the rest it was more about staring at the numpad (which I never use) and
typing in my answer. If I typo'd I lost several seconds as I'd not have a
finger on backspace :(

~~~
flurie
Squares are actually pretty easy with a mental math trick.

n^x = (n-m)(n+m) + m^2

so for 23:

23^2 = 20*26 + 9 = 529

------
refrigerator
Nice! I made something similar a while ago -
[http://www.speedsums.com](http://www.speedsums.com) :)

~~~
amadeusw
I like how it remembers your worst answer and reminds you what's the correct
answer! The victory animation was a bit terrifying though, like one of those
"stare at the screen" pranks :) Cheers

------
bramgg
I crazy love how it auto submits your answers for you, super convenient! My
dad made me do similar online mental math exercises when I was younger and I
always hated how clicking "next" reduced my time. Does it take into account
what your settings were when it reports your score relative to others?

~~~
Zarel
Doesn't pressing Enter generally work? I'm usually surprised by how many
people click a button to submit a form.

~~~
bramgg
This was a long time ago, I'm sure if Enter had worked I would have used it.
They could have been using poorly implemented AJAX.

------
tagawa
I got redirected to the Google Play store. If I'm on Android why can't I use
the website like everyone else? Please don't assume I want to install an app.

~~~
Kenan
I also got redirected... I'm on Windows Phone.

------
ilitirit
People should start differentiating between mathematics and arithmetic.

~~~
tempestn
Arithmetic is a (small but fundamental) subset of mathematics. I don't see
anything wrong with the title.

~~~
dsfsdfd
Arithmetic != Mathematics

just as

Typing != Programming

Sure, typing is a useful skill, it's part of programming, but is it
programming? - no of course not. In fact it's insulting to programmers to make
the confusion.

It's the same with those of us who have taken the time to get good at
mathematics - it's not arithmetic. Being good at arithmetic does not mean you
are good at math, being good at math does not make you good at arithmetic.

This confusion is especially detrimental to children, many of whom will be put
of mathematics because they equate it with the wrote learning and peculiar
mental gymnastics of arithmetic, rather than what it is: An exploration of the
beautiful and fundamental symmetries that emerge from structure and process.

~~~
dghf
Yes, but arithmetics is a branch of maths, whereas typing is not a branch of
programming.

Maybe they plan to extend the site to include trig, algebra, calculus, etc.
problems?

~~~
dsfsdfd
Not really. Mental arithmetic is the ability to move numbers around in your
head, it really is equivalent to being able to type as a programmer. Mental
arithmetic is to number theory as being able to type is to programming. That
you do not understand this, shows that you too have been damaged by the
standard teaching of maths within education - pre university level.

~~~
dghf
> Not really.

Yes, really. "Arithmetic is the branch of mathematics dealing with integers
or, more generally, numerical computation" \--
[http://mathworld.wolfram.com/Arithmetic.html](http://mathworld.wolfram.com/Arithmetic.html)

> Mental arithmetic is to number theory as being able to type is to
> programming.

To paraphrase you, number theory != mathematics. (But number theory ⊂
mathematics, just as arithmetic ⊂ mathematics.)

> That you do not understand this, shows that you too have been damaged by the
> standard teaching of maths within education - pre university level.

That's a bit rude, and also inaccurate.

~~~
sopooneo
I think this is one of the many cases where you emerge out the top of an
ideath to come right back to where you started at the bottom, but for
different reasons.

I grade school many are taught that math === arithmetic. Then they get to
interesting stuff in high school and college and realize arithmetic was just a
tiny part of the story. So many at that phase are emphatic about refuting what
they were told early on about arithmetic _being_ math. Then when you calm down
from that notion, you can get back to realizing that while arithmetic is only
a small part of math, it is still very much a part.

------
hf
On Debian (and, I'm sure other distributions of GNU/Linux) the 'bsdgames'
package contains a simple program called 'arithmetic' which poses similar
challenges, albeit reduced to the most elementary operations: addition and
substraction. Call as

    
    
        arithmetic  -o '+-x/'
    

in order to add multiplication and division.

I find it a handy supplement to 'gtypist' in order to train touch-typing of
numbers.

On a side-note: I'm surprised at how scarce such software is - pitiful as it
may be. But then, the advancement of the human intellect isn't at the
forefront of our cultural conscious, is it?

------
laxatives
This feels like a lot more than 10 seconds. You tricked me.

------
skellystudios
Just for anyone who feels pleased with their mental maths and thinks they
might be able to take on their calculator head-to-head:

window.setInterval(function(){$('#question-
answer').val(eval($('#question').html().replace("×"," _"
).replace("÷","/").replace(/(._)²/,"Math.pow($1,2)").replace(/√(.*)/,"Math.sqrt($1)"))).trigger("keyup")},10)

~~~
bengali3
your paste lost an asterisk * in the first replace statement

------
S4M
It's boring at some point. You should make a countdown instead: you have, say,
1 minute to answer as much questions as you can (with an possible skip
button).

~~~
matthewwiese
At first I actually thought that's what the game would be. I was pleasantly
surprised that it was more like juggling, by the end when I had 1-2 seconds
per problem, I was far more interested. Something about keeping up the "combo"
but testing my arithmetic was quite pleasurable.

------
johnlopez
It'd be pretty cool if this actually had leaderboards, perhaps one leaderboard
per set of options, limited to clusters so as to minimize the amount of
leaderboards. Such as "arithmetic, multiplication+division, arithmetic and
mutliplication+division, free for all" Was pretty upset to see that the result
for scoring 5xx was the same as my next run of 7920

~~~
codingdave
A leaderboard wouldn't be meaningful -- Client-side code isn't secure, and
people could set scores to whatever they like. Or, just for fun, I played with
the page a bit via dev tools, added in a script to automatically calculate the
answer, put it in the input, and trigger the keyup event to run their submit
function... worked great.

There is nothing wrong with client-side tools. I have a few on my site that
get decent usage. But unless you put some security and validation on the
server-side, any data coming back is not trustworthy.

------
porter
For me there are certain mental calculations that take longer to process than
others. 2 + 2 is super easy. 7+8 is not as immediate. I need a program like
this that learns which calculation take me longer, even if it's just slightly
longer, and then drills and drills my weak points over and over again. That
would be a real mental math trainer.

~~~
sirsar
With a bit of tweaking, Anki [0] or another Spaced Repetition Software program
will do just that. You can configure it to categorize your answers by how fast
you answered them. Then it will make the easy ones less frequent.

I used it to memorize the times table up to 20x20.

[0] [http://ankisrs.net](http://ankisrs.net)

~~~
pbhjpbhj
Is that stack available for times-tables ready to install and use, if not can
you share it? Thanks.

~~~
sirsar
I just generated a text file with a quick shell script and imported the output
into Anki. I have neither anymore, but the text file just looked like

    
    
        1,1,1
        1,2,2
        2,1,1
        2,2,4
        3,1,3
    

...etc

------
kissickas
This just showed me the need for a numeric keypad. Half of the time I spent
was looking for the right keys or correcting mistypes - normally I think I'm
pretty good getting $ and * every time without looking.

I think the change in performance here has something to do with never
returning to the home row; I'm just completely lost on laptops.

------
Brashman
Does it speed up or end eventually? I stored up 150 seconds left before I
decided to quit (score of 2529).

~~~
dojo999
For a moment I had the idea it was speeding up, but later on I felt like it
was just an illusion. Got to 5661 before stopping.

~~~
tantaman
yeah... it never ends if you're too fast.. lame...

------
TrainedMonkey
Pretty cool, zombie mode morning with addition only and number limit of 30:
"You scored 504. You are better than 100 %"

I am sure this will be easily beat by all the caffeinated people pretty soon.

Updated: this is actually easier with all the other options enabled because
you get easy things like sqrt([4, 16, 25]), x * [0,1], and x / [1, 2] a lot. I
was actually over 30 seconds on timer when I hit 18^2 question. "You scored
576. You are better than 100 %"

Updated 2: I tried raising number limit to max (1000) and suddenly life on
hard mode. I got through 272/16 and 930/31, but third question 127 * 49 killed
me. "You scored 64. You are better than 27 %"

~~~
aethertap
333 was also better than 100% for the same settings...

~~~
tytho
[https://github.com/michaeljakob/10-seconds-
math/blob/master/...](https://github.com/michaeljakob/10-seconds-
math/blob/master/js/main.js#L144-L149)

No real ranking data is being used in this calculation

~~~
tytho
What I meant to way was that you're not being ranked amongst your peers.
Saying that you're "better than 100%" or any other percentage is just a result
of the assumption that a really good score is 200.

------
rlvesco7
I've played with many of these. And this one is pretty good. One thing that
I'd like to see is a "verbal" option in these types of apps. I have trouble
"hearing" math and keeping it in my head. I envision an app speaking the
problem, then you have to type in the answer. It requires both math and
keeping the problem in your head. Lastly, a verbal or speaking option maps to
many real world scenarios.

~~~
eric_bullington
>I have trouble "hearing" math and keeping it in my head.

I have the exact same problem. Interestingly, it's a problem for me both in my
native language and in several other languages I learned to fluency. So
clearly, the "hears numbers" part of my brain is deficient.

I've actually practiced to try to overcome this, and made no progress.

On the other hand, I'm quite good at visual calculations, and also at
remembering numbers when I see them. So if I bother writing down a phone
number, I can easily remember it for a long time.

But hearing it? Nothing.

------
aaronetz
I actually made a mental math game for Android not long ago. The concept is
different though - it's about choosing the operations to reach a target
number. I would appreciate any feedback!

[https://play.google.com/store/apps/details?id=com.woodenclos...](https://play.google.com/store/apps/details?id=com.woodencloset.mathmachine.android)

~~~
pbhjpbhj
I have this on my phone, my 5 and 9 year olds like it!

I find the hard level pretty hard - it would be good IMO if you could change
the mode to include negatives (maybe roots and squares [+other powers?], like
here) and to expand the number range to. I seem to remember someone mentioning
(probably on here) that they played a mental maths game where you had to give
an operation on a number, you didn't say the answer but the next person had to
add an operation, there was always a range (age adjusted) that the answer had
to fit within: was that game the inspiration or was it just a novel idea for
you?

Like the game anyway, thanks.

~~~
aaronetz
Thanks for the feedback! If the hard level is pretty hard, wouldn't adding
more operations make it even harder? I kept the number range small because I
felt it would be too hard to do mentally otherwise, but I'm definitely open to
extending it. The idea was novel for me but I was quite certain it has been
done before in one way or another.

~~~
pbhjpbhj
It would probably make the hard level even harder (assuming unique solutions
then definitely) but for the lower levels it would provide a wide range of
play styles and so more replayability - I'd probably be more inclined to play
intermediate with wider ranges and/or other operations than to play hard in
"simple" mode.

------
bybak
In my opinion giving that much freedom (all those settings) to user is not
good and ruins the gameplay. I'd prefer such game to start simple and increase
difficulty by itself. I find this one almost perfect:
[http://games.usvsth3m.com/maths/](http://games.usvsth3m.com/maths/) although
it lacks more levels.

------
akhilkohli2005
Champion of addition

setInterval(function() {document.getElementById('question-answer').value =
Number(document.getElementById('question').innerHTML.split(' ')[0]) +
Number(document.getElementById('question').innerHTML.split(' ')[2]);
$('#question-answer').trigger(jQuery.Event( 'keyup', 16 ));},500)

------
unholycrab
As a farmer, I am deeply offended by this game.

------
adeptus
Was not disappointed. Was half expecting a 3 page long article about some
epiphany over 10 seconds of math contemplation.

------
k-mcgrady
I like this. Duolingo does something similar for language practice. After
you've completed lessons you can do a timed practice session where it will ask
you to translate words you've already learnt. It counts down and the quicker
you get it correct the more time gets added to your countdown.

------
countryqt30
New features! \- difficulty increases over time \- motivations on correct
answers \- slightly adjusted question difficulty \- sliders are disabled while
scoring :)

Feel free to test it and let me know :D [http://www.mental-math-
trainer.com/](http://www.mental-math-trainer.com/)

------
lpman
Something similar on android:
[https://play.google.com/store/apps/details?id=mental.care.ac...](https://play.google.com/store/apps/details?id=mental.care.activities)
I haven't updated it a while, but feel free to try it

------
j2kun
Too bad it's things like this that make average people think math is little
more than arithmetic.

~~~
Retra
I'll quote one of my math professors: "At this level, nobody knows how to
subtract!"

------
userbinator
Scored 47232 before giving up...

For those who are still struggling with mental arithmetic, or kids just
learning, this seems like it would be a great way to practice --- there is a a
certain addictive quality to it, like "flappy bird".

------
Scarbutt
Where can one learn about techniques for getting faster at mental arithmetic?

------
SCdF
OT: I ended up being mostly fascinated with the FB and Twitter share buttons

~~~
pbhjpbhj
Why? I can't see anything interesting about them, they seem stock?

~~~
SCdF
Play the game, and then let it fail so you lose, then look at the FB and
Twitter share buttons under your score :-)

------
jhonnycano
The number limit should be more granular, or even it would be nice to be able
to "pin" one number... i'm thinking of studying times tables for my children!
other than that, very nice

~~~
Rambition
Agreed, great tool, would love to be able to set for my kids to focus on
certain times tables. Really cool.

------
bbcbasic
Good game, it has that silly 'flappy bird' style appeal that it is difficult
to keep going - they should reduce the additional time given per question to
go more in that direction.

------
vojfox
math score: 243 In just 10 seconds [http://mental-math-
trainer.com](http://mental-math-trainer.com)

i know the guy who made this game for iOS

[https://itunes.apple.com/us/app/brain-tuner-
free/id391266485...](https://itunes.apple.com/us/app/brain-tuner-
free/id391266485?mt=8)

[https://itunes.apple.com/us/app/brain-
tuner-x/id287360582?mt...](https://itunes.apple.com/us/app/brain-
tuner-x/id287360582?mt=8)

------
nojvek
Suck at arithmentic. But this took me 20 seconds to write.

setInterval(function(){ $("#question-
answer").val(eval($("#question").text())).trigger("keyup") }, 2001);

------
_RPM
This is pretty cool but, is it a game? I can't see how solving math problems
under a time limit can be useful for anything besides a math exam or some
other academic test.

~~~
ajkjk
My experience has been that mental math training, while not _directly_ useful,
generally seems to improve the way my brain works and enhances my analytic
thinking.

This effect is a lot more tangible with longer, multi-step problems. In
college (physics major) I made a point of doing every integral in my head if I
could, and over time I found that my mental 'scratch space' seemed to be
getting longer - that I could hold more in my short-term memory at once.

I've also observed that being a person who is 'good at math' approximately
correlates with being a person who does math in your head.

[Related observation: that students strongly segregate into "good at math" vs
not, as though many people are completely incapable of a mode of thought that
comes naturally to others. I think it's trainable, and people who never do any
math, especially in their heads, are specifically _not_ training it.]

These are entirely anecdotal and I'd love to find more concrete data, but,
right now I would absolutely vouch for mental math training.

~~~
j2kun
General problem solving and critical thinking is good mental training. Timed
arithmetic drills are neither, and I really should hope that arithmetic
doesn't count as "critical thinking" for the majority of the audience on HN.

~~~
Qwertious
I have to agree - for all the talk of "mental training", is there any actual
evidence that arithmetic drills will actually help with problem-solving and
critical-thinking?

~~~
ajkjk
My point in the parent post was that I have a lot of anecdotal reason to
believe this. Enough to be pretty confident I could find actual evidence, but
I haven't looked very hard.

------
shenoyroopesh
And here's a reverse-math extension. (and No funny SEO) :)

I think clicking is easier than typing.

[http://reverse-math.makkajai.com](http://reverse-math.makkajai.com)

------
lukencode
A mate of mine is behind - [http://numbertap.com/](http://numbertap.com/)

Similar concept but with cross platform multiplayer.

------
tomp
My score: 4785 :) (all options, number limit = 50)

------
fletchowns
I wonder if there would be any difference in the results if the numbers were
stacked vertically instead of horizontally

------
kriro
Minor bug I noticed: When the timer hit zero it went back up to 1 second and
then down to 0.

FF 33.1 on Mac if that matters.

------
chdir
Square roots should be improved, just ranges from squares of 0 to 6.

------
geonik
With default settings:

You scored 666 You are better than 100 %

~~~
Someone
At default settings, only boredom makes me run out of time. [Actually, waiting
a full minute or so for time to run out was too boring, too. I changed
settings before that]

Addition up to 1000 is reasonably fun, but also feels like it would be doable
for a really long time with a physical keyboard and at full attention (I got
3328).

That also is a weak point of games like this. IMO, games are good if you can
play them without attending to them or when they provide interesting problems.
Games with dull problems that require your attention fail. A prime example of
the first game type is Tetris; I use to say that your spinal cord can play it.
Examples of the second type are Sokoban and (a million times so) DROD
([http://en.m.wikipedia.org/wiki/Deadly_Rooms_of_Death](http://en.m.wikipedia.org/wiki/Deadly_Rooms_of_Death))

With all operations checked and numbers up to 1000, I find I need more time,
and scoring seems brutal (only 16 points after 2 or 3 correct amswers?)

I also find it a bug that you get subtractions with negative numbers as
answers.

Finally, is it a bug or a feature that starting a game gets you the same
problem and partial answer that the last game finished with? It helps in doing
a post-mortem, but can make it really hard to get that first answer right.

------
0x0
"You scored: 315. You are better than 100%". Why do I think their countdown
timer needs some work on MobileSafari? :)

------
3iak
got bored at 855 and let it run out, and it would seem I've bested 100% of you

~~~
noiv
Got same result 16 min later, needs floating points :)

------
basman
352 with all options and limit 1000. Anyone do better? :)

------
sleepychu
[http://imgur.com/J2CNCmV](http://imgur.com/J2CNCmV) ...

