Maths Puzzles please

**DimPrawn** · 17 March 2010, 11:23

http://mathworld.wolfram.com/GoldbachConjecture.html

**Platypus** · 17 March 2010, 11:25

Originally posted by DimPrawn View Post

http://mathworld.wolfram.com/GoldbachConjecture.html

Thanks, but I was thinking more along the lines of 'party trick' puzzles, not stuff you need a maths degree to even read

**realityhack** · 17 March 2010, 11:27

http://classroom-activities.suite101...and_number_fun

There's a few ones there that might do the job.

**MarillionFan** · 17 March 2010, 11:28

http://easycalculation.com/funny/tricks/trick1.php

Personally I've always like the divisible by three trick. To see if a number is divisible by three adds it components

So 723 = 12, so is divisible by 3 (ie 241)
126 = 9 so is divisible etc

**Cliphead** · 17 March 2010, 11:28

Here's an interesting one.

Write on a piece of paper the words

Denmark
elephant
gray

And put on a table with the words hidden. You're going to read someone's mind.

Ask your victim to

think of a number between 1 and 10
ask them to multiply that number by 9
ask them to add the two digits of the answer together (if they though of 5 - 5x9=45, 4+5=9 etc)

Ask them to subtract 5 from that number - it will always be 4

Tell them that the number they're left with will correspond to the letters of the alphabet - 1=a, 2=b etc.

Ask them to think of a country that begins with the letter corresponding to their final answer (4), will almost always be Denmark.

Ask them to think of an animal that begins with the second letter of that country - will almost always be an elephant.

Ask them what colour the animal they're thining of is - gray

Then turn over the piece of paper - mind reading.

**fullyautomatix** · 17 March 2010, 11:30

2 + 2 = always 4.

Unless you are the UK chancellor of the exchequer in which case the figures do not add up !!!

**EternalOptimist** · 17 March 2010, 11:38

How old is the lad Platypus ?

when my kids and grandkids were about 5 or so, and starting to take an interest, i got them to take 5 away from three. This frys their noodle because its not possible. so that leads on to explain minuses, the concept of 'owing', compound interest and saving. It's the sort of thing you can come back to over the years, as their brains develop.

another one, muliply any number by 9. add the result, it will equal 9.
9*3 = 27. 2+7 = 9

**Platypus** · 17 March 2010, 11:39

Originally posted by Cliphead View Post

Here's an interesting one.

Write on a piece of paper the words

Denmark
elephant
gray

etc.

Along similar lines, I received this one by email recently:

A little test for you

At the end of this message, you are asked a question.
Answer it immediately..
Don't stop and think about it.

Just say the first thing that pops into your mind..
This is a fun 'test'... AND kind of spooky at the same time!

Now - just follow the instructions as quickly as possible.

Do not go to the next calculation before you have finished the previous one.. You do not ever need to write or remember the answers, just do it using your mind.

You'll be surprised.

Start: How much is: 15 + 6

21

3 + 56

59

89 + 2

91

12 + 53

65

75 + 26

101

25 + 52

77

63 + 32

95

I know! Calculations are hard work, but it's nearly over..

Come on, one more! .....

123 + 5

128

QUICK! THINK ABOUT A COLOUR AND A TOOL!

Scroll further to the bottom.....

A bit more...

You just thought about a red hammer , didn't you?

If this is not your answer, you are among 2% of
people who have a different, if not abnormal, mind.

98% of the folks would answer a red hammer while doing this exercise.

**Cliphead** · 17 March 2010, 11:42

Originally posted by Platypus View Post

You just thought about a red hammer , didn't you?

If this is not your answer, you are among 2% of
people who have a different, if not abnormal, mind.

98% of the folks would answer a red hammer while doing this exercise.

I got a green hammer

Maths Puzzles please