20 - 0 = 20
21 - 1 = 20
22 - 2 = 20
23 - 3 = 20
24 - 4 = 20
25 - 5 = 20
So the possible answers with doing just half the work are:
These aren't our answers though because we've only done half the work.
So now lets subtract the first digit from each of these (and since the
tens digit only changes every ten numbers, we only need to do it on
these numbers). In doing so, we end up with:
As luck would have it, these are the numbers you see on the right column!
So lets look at the answer key. I've highlighted our answers from above:
Lo and behold, all of our answers are the same symbol! This means that no
matter which one you picked, your symbol is the smiley face.
So pick one. Are we right? Of course!
Clicking the ball reveals:
This animation is tricky though! Once you click the ball the answer key
dissapears so you can't easily see what other answers have the same symbol.
That's not all though, when you try again, Andy randomly changes the symbols!
Rest assured though; every time you play it our correct answers
will always be the same symbol, and correct no less.
I've heard some people say that they tried and got it wrong.
There are two possible reasons for it.
The first and most likely reason is human error; you goofed!
Either you did the math wrong or you remembered the wrong symbol.
The second and rarest (and perhaps not even possible!) reason
is trickery; he may occassionaly make it error. If any one of the
numbers I listed wasn't the correct symbol, then this is the case.
The proof of this? Call the two digit number xy
and you can simplify as such:
(10x + y) - (x + y) = 9x
So any multiple of 9 will be correct here.
All in all a fun and creative Flash application. Good job Andy!
It appears that Andy is now explaining how it works if you pay him
to do so. I know what it's like to spend a lot of time working
on projects that don't produce revenue (and often cost you!), such as this
website you're reading right now, but can't say I agree with
accepting money for math tutoring... Especially when what you're
doing has been done time
after time (even pages like this
which explain it can be found again
Thanks to the freedoms we enjoy, this page has come to you absolutely free,
even though this page caused me to exceed my bandwidth limits
and forced me to move to a commercial website host!
I'm paying for you to read this, so I hope you enjoyed it. :-)