The Beauty of Mathematics!

Hey guys! I haven't invented these - I just collected them.

Let's start with general definition.

Mathematics is made of 50 percent formulas, 50 percent proofs, and 50 percent imagination.

-------------------------------------------------------------------------------------
The Numbers 1 to 9

The sum of 1+2+3+4+5+6+7+8+9 = 45

Multiply 123456789 by 2 and you get 246913578, the sum of which is 45

The "stations" of the nine times table all add up to nine. 9, 18, 27, 36, 45, 54, 63, 72, 81, 90
-------------------------------------------------------------------------------------

Maths Trick
Try this one in your head, using mental maths...

Step 1
Ask a friend to think of a number between 1 and 10.
Example: 8

Step 2
Get them to double it.
Example: 16

Step 3
Ask them to add 10 to the answer.
Example: 26

Step 4
Then get them to divide by 2.
Example: 13

Step 5
Ask them to tell you what number they now have.
Example: 13

Step 6
You subtract 5 from this and tell them what their original number was.
Example: 13 - 5 = 8
-------------------------------------------------------------------------------------

Amazing 1089

Step 1
Take two pieces of paper and hand one to a friend.
On yours, without letting them see, write the number 1089, then fold the paper to keep it hidden.

Step 2
Ask them to think of a 3-digit number but, before they write it down, ask them to put the numbers in order from greatest to smallest. Don't let them show what they've written.
Example: 543

Step 3
Below their number, ask them to write the same digits, but in reverse order, from smallest to greatest.
Example: 345

Step 4
Now, ask them to subtract the new lower number from the original one they wrote.
Example: 198

Step 5
Next, ask them to reverse the order of that number.
Example: 891

Step 6
Then, get them to add this latest number and the previous number together and show you the result.
Example: 891 + 198 = 1089

Step 7
Finally, you can reveal your own number, which (if they have calculated correctly) will be exactly what they have written... 1089
-------------------------------------------------------------------------------------

Maths Trick

STEP 1
Ask a friend to write down a number (any number with more than 3 digits will do, but to save time and effort you might suggest a maximum of 8 digits).
Example: 83 972 105

STEP 2
Ask them to add the digits.
Example: 8+3+9+7+2+1+0+5 = 35

STEP 3
Ask them to subtract this number from the original one.
Example: 83 972 105 – 35 = 83 972 070

STEP 4
Ask them to select any digit from this new number and strike it out, without showing you.
Example: 83 972 070

STEP 5
Ask them to add the remaining digits and write down the answer they get.
Example: 8+3+9+7+0+7+0 = 34

STEP 6
Ask them to tell you the number they get (34) and you will tell them which number they struck out.

SOLUTION
The way you do this is to subtract the number they give you from the next multiple of 9. The answer you get is the number they struck out.
Example: The next multiple of 9 here is 36 (9 x 4 =36)
36 – 34 = 2 and there you have your answer, easy isn’t it!

Note: If the number they give you after step 5 is a multiple of 9, there are two possible answers then you simply tell them that this time they crossed out either a 9 or a zero.
-------------------------------------------------------------------------------------

Finger Math: 9X Rule

To multiply by 9,try this:

Spread your two hands with all fingers open out and place them on a desk or table in front of you.

To multiply by 3 (ie. 3 X 9), fold down the 3rd finger of your left hand (from the left hand side). To multiply by 4, it would be the 4th finger and so on.

The answer is 27 (ie. 3 X 9 = 27), ... HOW TO READ IT ???? We have 2 fingers at the left most side of the finger which is folded in left hand and the 7 fingers on the right of it (ie 2 fingers at right of folded finger of left hand and all 5 fingers of right hand).

This works for anything up to 9x10!
-------------------------------------------------------------------------------------

The 11 Rule

To multiply any two digit number by 11:
For this example we will use 54.
Separate the two digits in you mind (5__4).
Notice the hole between them!
Add the 5 and the 4 together (5+4=9)
Put the resulting 9 in the hole 594. That's it! 11 x 54=594

The only thing tricky to remember is that if the result of the addition is greater than 9, you only put the "ones" digit in the hole and carry the "tens" digit from the addition. For example 11 x 57 ... 5__7 ... 5+7=12 ... put the 2 in the hole and add the 1 from the 12 to the 5 in to get 6 for a result of 627 ... 11 x 57 = 627
Practice it on paper first!
-------------------------------------------------------------------------------------

Theorem: 1$ = 10 cent

Proof: We know that $1 = 100 cents

Divide both sides by 100

$ 1/100 = 100/100 cents

or, $ 1/100 = 1 cent

Take square root both side

or, squr($1/100) = squr (1 cent)

or, $ 1/10 = 1 cent

Multiply both side by 10

or, $1 = 10 cent

Hahaha Funny!!!
-------------------------------------------------------------------------------------

Salary Theorem
The less you know, the more you make.

Proof:

Postulate 1: Knowledge is Power.
Postulate 2: Time is Money.

As every engineer knows: Power = Work / Time
And since Knowledge = Power and Time = Money

It is therefore true that
Knowledge = Work / Money

Solving for Money, we get:
Money = Work / Knowledge

Thus, as Knowledge approaches zero, Money approaches infinity, regardless of the amount of Workdone.
-------------------------------------------------------------------------------------