Korean Job Discussion Forums

[patchy]

http://www.mysticalball.com/

Try this site out.

[the eye]

it just shows the symbol corresponding to multiples of '9' over and over again. it's just math.

[tomato]

Sorry, but I've seen this trick before.
Any result you get will give you a multiple of 9.
All the designer does is keep changing the symbols for the multiples of 9.

Here's a trick which one of my classes liked:

Write 1 2 3 4 5 6 7 8 9 on the board.
Say, "Suzy, which one is your favorite number?"
Suzy chooses 5.
Say, "Let's all do Suzy a favor."
Then write 37 x 15 on the board.
When all the students finish the problem, the answer should be 555.

Say, "Johnny, which one is your favorite number?"
Johnny chooses 7.
Say, "Let's all do Johnny a favor."
Then write 21 x 37 on the board.
When all the students finish the problem, the answer should be 777.

Get it?
The trick is to mentally multiply the chosen one-digit number by 3.
Then ask the students to multiply that number by 37.
Since 37 x 3 = 111, the answer will always be a string of the same one-digit number.


Here's another number trick:

http://www.eslcafe.com/forums/korea/viewtopic.php?t=54525&highlight=

[patchy]

Oh damn, you guys spoiled it already ... I wanted some people to try it out and figure out how it worked themselves. I know I was amazed.

[tomato]

That's okay, Patchy.
You got me thinking about number tricks.
Here is another of my favorites:

Ask a student to choose a number between 1 and 15 and show it to the rest of the class but don't show it to you.
(That's a little hard for them to understand in English.
Sometimes I have to give the instructions the quick and dirty way.)

While that is going on, I write four lists of numbers on the board.

The first list is: 1 3 5 7 9 11 13 15

The second list is: 2 3 6 7 10 11 14 15

The third list is: 4 5 6 7 12 13 14 15

The fourth list is: 8 9 10 11 12 13 14 15

Without even looking at the board, ask,
"Is it on the first list?"
If the student says yes, mentally add 1.

"Is it on the second list?"
If the student says yes, mentally add 2.

"Is it on the third list?"
If the student says yes, mentally add 4.

"Is it on the fourth list?"
If the student says yes, mentally add 8.

There is no telling who will guess the secret and who won't.
I've had third graders who quickly guessed the secret, and I've had people with advanced degrees in math who couldn't.