Phone Number Trick

Here is a math trick so unbelievable that it will stump you. Personally I would like to know who 

came up with this and why that person is not running the country.

1. Grab a calculator. (you won't be able to do this one in your head)

2. Key in the first three digits of your phone number (NOT the area code)

3. Multiply by 80

4. Add 1

5. Multiply by 250

6. Add the last 4 digits of your phone number

7. Add the last 4 digits of your phone number again.

8. Subtract 250

9. Divide number by 2

Do you recognize the answer ??????

THE AMAZING MATH TRICK OF 1999

1.  First of all, pick the number of days a week that you

would like to eat out.

 

2.  Multiply this number by 2.

 

3.  Add 5.

 

 4.  Multiply it by 50.

 

5.  If you have already had your birthday this year . . .

add 1749.

If you have NOT had your birthday yet this year . . .

add 1748.

 

6. Last step: Subtract the four digit year that you

were born.

You should now have a three digit number:

 

The first digit of this was your original number (i.e.

how many times you want to go out to eat each week).

 

The second two digits are your age !!!

 

This is the only year it will ever work, so spread the

fun around while it lasts . . .

The Prime Number Trick

Using prime numbers, you can amaze your friends with a prime prediction...

 

Ask your friends to pick any prime number bigger than 5, but they must not tell you what it is.

 

Square it. (In other words multiply the prime number by itself.)

 

Add 17

Divide by 12

Without knowing which prime number your friends picked, you can still tell them:
 

There will be a remainder of 6.

 

 

For example, if you want to try the trick with the prime number 2801, here's what to 

push:

 

2801 * 2801 =
 

+ 17 =
 

/ 12 =

 

...and that's the answer! Now find a new prime number and try it.

The "24" Mystery!

A Murderous Math fan called OBAID pointed out that if you square ANY prime number 

bigger then 3, then subtract 1, the answer always divides by 24! E.g. 112 = 121 then 121 - 

1 = 120 and yes 120 does divide by 24. 

 

WHY? 

 

If you understand algebra, (and you've read The Phantom X ) then you'll know that all 

prime numbers can be written as (6n+1) or (6n-1). 

 

(6n+1)2 = 36n+12n+1. So (6n+1)2 -1 = 36n+12n. This factories to 12n(3n+1). Either n or 

(3n+1) must be even, therefore the whole expression must be divisible by 24.

 

(6n-1)2 = 36n-12n+1. So (6n-1)2 -1 = 36n-12n. This factories to 12n(3n-1). Either n or 

(3n-1) must be even, therefore the whole expression must be divisible by 24.

Rain Detector

Rain Detector:

Rain detector or rain sensor is a circuit that is used to detect or sense rain i.e. as soon as the rain droplets fall on the sensor it triggers an alarm or a buzzer or any other device that is used to indicate the presence of rain (water).

Specified Problem:

The problem given was to make a rain detector circuit that glows an LED when there is no rain droplets or water on the sensor and when it rains i.e. is water droplets are present on the sensor it turns of the LED that was previously glowing to show the absence of rain and then simultaneously turns on a BUZZER and another LED which indicates the presence of rain or water droplet on the sensor. Moreover the BUZZER and the LED (used to indicate rain) was to glow and buzz with some constant time interval i.e. it remains on for some  certain time (seconds) and then goes off for some certain time(seconds) and then goes on again repeating this until the rain or water droplets are present there.

Designed Circuit:

The problem given was solved by designing a circuit which works according to the given specification i.e. the switching between the two LEDs was achieved by using a SPDT (Single Pole Double Through) RELAY and the timing of the buzzer and the other LED was achieved by using the 555 timer IC.

Components Used:

·   Relay

·   555 Timer IC

·   Resistors

·   Capacitor

·   LEDs

·   Sensor

·   DC supply

·   Buzzer

Working:

The circuit connected as in the circuit diagram given below. The connections are done in such a way that one leg of the relay is directly connected to 12Volts while one leg is connected to 12Volts via sensor, one leg of the relay is connected directly to ground while the remaining two are connected to the LED indicating the absence of rain and the other to the LED and BUZZER indicating the presence of rain respectively. The arrangements made on the legs of relay are made in accordance to the circuit diagram and the relay connections.

When there is no rain the 12Volts which are directly connected to the rain passes through the relay and via resistor turns on the LED to indicate the absence of the rain or water.

As soon as the rain or water droplets are detected on the sensor the circuit is completed and the current flows through the sensor which magnetizes the coil of the relay thus it shifts to its second through which is then connected with the buzzer and the LED (used to indicate the presence of water or rain) via resistor, when this happens the current flows through this half of the circuit thus causes the buzzer and the LED to glow and indicate the presence of rain , the timing of the buzzer is achieved by the 555 timer IC which is given above in detail.

The circuit again turns to the original state of no rain when there is no rain or water on the sensor i.e. the rain has stopped and the sensor is dry.

AC-DC, switch to glow LED and BUZZER

GENERAL DESCRIPTION:

Ø In this project , LED glows when AC supply  is on and as soon as AC cuts off circuit switch to DC supply and then  LED and BUZZER is turn on which is controlled by a switch. In this circuit we use a Relay for switching

COMPONENTS USED:   

 Step-Down transformer (240V to 12V).

  Bridge-Rectifier(w04M).
  
   LEDs (3mm x2).

 

                  Buzzer (6V).

     

   Relay (12V DC-SPDT).

   General purpose PCB sheet

  

         DC source (9V battery).

WORKING:

Ø First of all 220V is step-down to 12V by a step-down transformer.

Ø Bridge Rectifier then convert this 12V AC into DC.

Ø Then a resistance and a LED is attached in parallel to the rectifier.

Ø After this a 12V Relay is attached parallel with this circuit.

Ø A 9V battery with a switch, LED and a BUZZER is attached with the second pole of the Relay.

Birthday Trick

This math trick will determine your birthday. Just follow the steps with a calculator and press 

equal after each step. Go ahead and try the trick without cheating! For a simple, online 

JavaScript calculator, click on the calculator button.

1. Add 18 to your birth month

2. Multiply by 25

3. Subtract 333

4. Multiply by 8

5. Subtract 554

6. Divide by 2

7. Add your birth date

8. Multiply by 5

9. Add 692

10. Multiply by 20

11. Add only the last two digits of your birth year

12. Subtract 32940 to get your birthday!

The answer's format is: month/day/year. For example, an answer of 123199 means that you 

were born on December 31, 1999. If the answer is not right, you followed the directions 

incorrectly or lied about your birthday.

The MISSING DIGIT trick!

Here it is!

 

Go and hide in a cupboard, or cover your eyes in some way so that you can't see what your 

friend is writing.

 

Ask a friend to secretly write down ANY number (at least four digits long). e.g. 78341

 

Ask the friend to add up the digits... e.g. 7+8+3+4+1 = 23

 

... and then subtract the answer from the first number. e.g. 78341 - 23 = 78318

 Your friend then crosses out ONE digit from the answer. (It can be any digit except a zero) e.g. 

 

7x318

 

Your friend then reads out what digits are left .e.g. 7-3-1-8

 

Even though you haven't seen any numbers, you can say what the missing digit is! EIGHT 

 

THE SECRET

 

 

This great trick relies on the power of 9.

 

After your friend has added up the digits and subtracted them, the answer will ALWAYS divide 

by 9. If a number divides by nine, then when you add the digits up, they will also divide by 9.

 

If you check our example 7+8+3+1+8 = 27 which does divide by nine.

 

When your friend crosses a digit out, he then reads out the digits that are left. You add them up. 

 

In the example we had 7+3+1+8 = 19

 

All you do now is see what you have to add on to your answer to get the next number that 

divides by nine! The next number to divide by 9 after 19 is 27. So you need to add on EIGHT. 

This is the number that was crossed out!