Funny Answers to School Tests

Clever and funny answers to maths questions. I think they actually show great capacity for lateral thinking.

Find X - Easy!

More funny exam answers and Diagrams

Math Magic / Phone Number / Missing Digit / Funny Tricks

Missing Digit  /Funny Tricks  / Math Magic /  Phone Number

Missing digit Trick
===-----===
Step1: Choose a large number of six or seven digits.
Step2: Take the sum of digits.
Step3: Subtract sum of digits from any number chosen.
Step4: Mix up the digits of resulting number.
Step5: Add 25 to it.
Step6: Cross out any one digit except zero.
step7: Tell the sum of the digits. Subtract the sum of the digits from 25.

Answer: Inorder to find out the missing digit, subtract the sum of digits from 25. The difference is the missing digit.

===========------------------===========

Phone Number trick

Step1: Grab a calculator (You wont be able to do this one in your head) .
Step2: Key in the first three digits of your phone number (NOT the area code-if your number is 01-123-4567, the 1st 3 digits are 123).
Step3: Multiply by 80.
Step4: Add 1.
Step5: Multiply by 250.
Step6: Add the last 3 digits of your phone number with a 0 at the end as one number
step7: Repeat step 6
step8: Subtract 250
step9: Divide number by 20

Answer: The 3 digits of your phone number

===========----------------===========

NEW DECEMBER TRICKS

Trick 1: Consecutive number trick

Step1: Pick any 5 consecutive numbers between ten and one hundred. Let's say your friend picks 51, 52, 53, 54, and 55.
Step2: Find the middle number, (call it the median). In your case, the median is 53.
Step3: Multiply it by ten (just add a zero to the median). eg. 53 X 10 = 530.
Step4: Divide (/) by 2. eg. 530 / 2 = 265.

Answer: That number is the answer -- the same as if we did the sum.

---

Trick 2: Number Trick For Fun

Step1: Think of a number from 1 to 10 
Step2: Multiply it by 9. 
Step3: Add the digits together.
step4: Subtract 5 from result of step3.
step5: Find the letter of the alphabet which corresponds to your number (1 = A, 2 = B, ...)
step6: Think of a country that starts with that letter.
step7: Think of an animal that starts with the last letter of your country.
step8: Think of a color that starts with the last letter of your animal.

Answer: It will always be an orange kangaroo in Denmark.

NEW TRICKS FOR 2009 DECEMBER

1. The 11 Times Trick

We all know the trick when multiplying by ten - add 0 to the end of the number, but did you know there is an equally easy trick for multiplying a two digit number by 11? This is it:

Take the original number and imagine a space between the two digits (in this example we will use 52:

5_2

Now add the two numbers together and put them in the middle:

5_(5+2)_2

That is it - you have the answer: 572.

If the numbers in the middle add up to a 2 digit number, just insert the second number and add 1 to the first:

9_(9+9)_9

(9+1)_8_9

10_8_9

1089 - It works every time.

 

2. Quick Square

If you need to square a 2 digit number ending in 5, you can do so very easily with this trick. Mulitply the first digit by itself + 1, and put 25 on the end. That is all!

25² = (2x(2+1)) & 25

2 x 3 = 6

625

 

3. Multiply by 5

Most people memorize the 5 times tables very easily, but when you get in to larger numbers it gets more complex - or does it? This trick is super easy.

Take any number, then divide it by 2 (in other words, halve the number). If the result is whole, add a 0 at the end. If it is not, ignore the remainder and add a 5 at the end. It works everytime:

2682 x 5 = (2682 / 2) & 5 or 0

2682 / 2 = 1341 (whole number so add 0)

13410

Let’s try another:

5887 x 5

2943.5 (fractional number (ignore remainder, add 5)

29435

 

4. Multiply by 9

This one is simple - to multiple any number between 1 and 9 by 9 hold both hands in front of your face - drop the finger that corresponds to the number you are multiplying (for example 9×3 - drop your third finger) - count the fingers before the dropped finger (in the case of 9×3 it is 2) then count the numbers after (in this case 7) - the answer is 27.

 

5. Multiply by 4

This is a very simple trick which may appear obvious to some, but to others it is not. The trick is to simply multiply by two, then multiply by two again:

58 x 4 = (58 x 2) + (58 x 2) = (116) + (116) = 232

 

6. Calculate a Tip

If you need to leave a 15% tip, here is the easy way to do it. Work out 10% (divide the number by 10) - then add that number to half its value and you have your answer:

15% of $25 = (10% of 25) + ((10% of 25) / 2)

$2.50 + $1.25 = $3.75

 

7. Tough Multiplication

If you have a large number to multiply and one of the numbers is even, you can easily subdivide to get to the answer:

32 x 125, is the same as:
16 x 250 is the same as:
8 x 500 is the same as:
4 x 1000 = 4,000

 

8. Dividing by 5

Dividing a large number by five is actually very simple. All you do is multiply by 2 and move the decimal point:

195 / 5

Step1: 195 * 2 = 390
Step2: Move the decimal: 39.0 or just 39

2978 / 5

step 1: 2978 * 2 = 5956
Step2: 595.6

 

9. Subtracting from 1,000

To subtract a large number from 1,000 you can use this basic rule: subtract all but the last number from 9, then subtract the last number from 10:

1000
-648

step1: subtract 6 from 9 = 3
step2: subtract 4 from 9 = 5
step3: subtract 8 from 10 = 2

answer: 352

 

10. Assorted Multiplication Rules

Multiply by 5: Multiply by 10 and divide by 2.
Multiply by 6: Sometimes multiplying by 3 and then 2 is easy.
Multiply by 9: Multiply by 10 and subtract the original number.
Multiply by 12: Multiply by 10 and add twice the original number.
Multiply by 13: Multiply by 3 and add 10 times original number.
Multiply by 14: Multiply by 7 and then multiply by 2
Multiply by 15: Multiply by 10 and add 5 times the original number, as above.
Multiply by 16: You can double four times, if you want to. Or you can multiply by 8 and then by 2.
Multiply by 17: Multiply by 7 and add 10 times original number.
Multiply by 18: Multiply by 20 and subtract twice the original number (which is obvious from the first step).
Multiply by 19: Multiply by 20 and subtract the original number.
Multiply by 24: Multiply by 8 and then multiply by 3.
Multiply by 27: Multiply by 30 and subtract 3 times the original number (which is obvious from the first step).
Multiply by 45: Multiply by 50 and subtract 5 times the original number (which is obvious from the first step).
Multiply by 90: Multiply by 9 (as above) and put a zero on the right.
Multiply by 98: Multiply by 100 and subtract twice the original number.
Multiply by 99: Multiply by 100 and subtract the original number.

 

Bonus: Percentages

Yanni in comment 23 gave an excellent tip for working out percentages, so I have taken the liberty of duplicating it here:

Find 7 % of 300. Sound Difficult?

Percents: First of all you need to understand the word “Percent.” The first part is PER , as in 10 tricks per listverse page. PER = FOR EACH. The second part of the word is CENT, as in 100. Like Century = 100 years. 100 CENTS in 1 dollar… etc. Ok… so PERCENT = For Each 100.

So, it follows that 7 PERCENT of 100, is 7. (7 for each hundred, of only 1 hundred).
8 % of 100 = 8. 35.73% of 100 = 35.73
But how is that useful??

Back to the 7% of 300 question. 7% of the first hundred is 7. 7% of 2nd hundred is also 7, and yep, 7% of the 3rd hundred is also 7. So 7+7+7 = 21.

If 8 % of 100 is 8, it follows that 8% of 50 is half of 8 , or 4.

Break down every number that’s asked into questions of 100, if the number is less then 100, then move the decimal point accordingly.

EXAMPLES:

8%200 = ? 8 + 8 = 16.
8%250 = ? 8 + 8 + 4 = 20.
8%25 = 2.0 (Moving the decimal back).
15%300 = 15+15+15 =45.
15%350 = 15+15+15+7.5 = 52.5

Also it’s usefull to know that you can always flip percents, like 3% of 100 is the same as 100% of 3.

35% of 8 is the same as 8% of 35.

Multiplication Tips

Multiplying by five

• Jenny Logwood writes: Here is an easy way to find an answer to a 5 times question.
  

  If you are multiplying 5 times an even number: halve the number you are multiplying by and place a zero after the number. Example: 5 × 6, half of6 is 3, add a zero for an answer of 30. Another example: 5 × 8, half of8 is 4, add a zero for an answer of 40.

  If you are multiplying 5 times an odd number: subtract one from the number you are multiplying, then halve that number and place a 5 after the resulting number. Example: 5 × 7: -1 from 7 is 6, half of 6 is 3, place a 5 at the end of the resulting number to produce the number 35. Another example:5 × 3: -1 from 3 is 2, half of 2 is 1, place a 5 at the end of this number toproduce 15.

• Doug Elliott adds: To square a number that ends in 5, multiply the tens digit by (itself+1), then append 25. For example: to calculate 25 × 25, first do 2 × 3 = 6, then append 25 to this result; the answer is 625. Other examples: 55 x 55; 5 × 6 = 30, answer is 3025. You can also square three digit numbers this way, by starting with the the first two digits:995 x 995; 99 × 100 = 9900, answer is 990025.

 Multiplying by nine

• Diana Grinwis says: To multiply by nine on your fingers, hold up ten fingers - if the problem is 9 × 8 you just put down your 8 finger and there's your answer: 72. (If the problem is 9 × 7 just put down your 7 finger: 63.)

• Laurie Stryker explains it this way: When you are multiplying by 9, on your fingers (starting with your thumb) count the number you are multiplying by and hold down that finger. The number of fingers before the finger held down is the first digit of the answer and the number of finger after the finger held down is the second digit of the answer.
  

  Example: 2 × 9. your index finder is held down, your thumb is before, representing 1, and there are eight fingers after your index finger, representing 18.

• Polly Norris suggests: When you multiply a number times 9, count back one from that number to get the beginning of your product. (5 × 9: one less than 5 is 4).
  

  To get the rest of your answer, just think of the add fact families for 9:

      1 + 8 = 9        2 + 7 = 9        3 + 6 = 9        4 + 5 = 9
  
      8 + 1 = 9        7 + 2 = 9        6 + 3 = 9        5 + 4 = 9
  

  5 × 9 = 4_. Just think to yourself: 4 + _ = 9 because the digits in your product always add up to 9 when one of the factors is 9. Therefore,4 + 5 = 9 and your answer is 45! I use this method to teach the "nines" in multiplication to my third graders and they learn them in one lesson!

  Tamzo explains this a little differently:

  1. Take the number you are multiplying 9 by and subtract one. That number is the first number in the solution.
  2. Then subtract that number from nine. That number is the second number of the solution.
  Examples:
  
  4 * 9 = 36
  
  1. 4-1=3
  2. 9-3=6
  3. solution = 36

  8 * 9 = 72

  1. 8-1=7
  2. 9-7=2
  3. solution = 72

  5 * 9 = 45

  1. 5-1=4
  2. 9-4=5
  3. solution = 45

• Sergey writes in: Take the one-digit number you are multipling by nine, and insert a zero to its right. Then subtract the original number from it.
  
  For example: if the problem is 9 * 6, insert a zero to the right of the six, then subtract six: 
  
  9 * 6 = 60 - 6 = 54
  

 Multiplying a 2-digit number by 11

• A tip sent in by Bill Eldridge: Simply add the first and second digits and place the result between them.
  

  Here's an example using 24 as the 2-digit number to be multiplied by 11:2 + 4 = 6 so 24 × 11 = 264.

  This can be done using any 2-digit number. (If the sum is 10 or greater, don't forget to carry the one.)

 Multiplying any number by 11

• Lonnie Dennis II writes in:
  

  Let's say, for example, you wanted to multiply 54321 by 11. First, let's look at the problem the long way...

  54321  x 11  54321  + 543210  = 597531

  Now let's look at the easy way...

  11 × 54321

  =	5	4+5	4+3	3+2	2+1	1
  = 597531

  Do you see the pattern? In a way, you're simply adding the digit to whatever comes before it.

  But you must work from right to left. The reason I work from right to left is that if the numbers, when added together, sum to more than 9, then you have something to carry over.

  Let's look at another example...

  11 × 9527136

  Well, we know that 6 will be the last number in the answer. So the answer now is

  ???????6.

  Calculate the tens place: 6+3=9, so now we know that the product has the form
  

  ??????96.

  3+1=4, so now we know that the product has the form
  

  ?????496.

  1+7=8, so
  

  ????8496.

  7+2=9, so
  

  ???98496.

  2+5=7, so
  

  ??798496.

  5+9=14. 
  
  Here's where carrying digits comes in: we fill in the hundred thousands place with the ones digit of the sum 5+9, and our product has the form
  

  ?4798496.

  We will carry the extra 10 over to the next (and final) place.
  

  9+0=9, but we need to add the one carried from the previous sum: 9+0+1=10.

  So the product is 104798496.

 Multiplying by thirteen

• Fourth grader Mariam Labib has a trick for multiplication by 13.

  Put the tens digit on the left, the unit number on the right, add them up together in the middle. Then add double the number to the previous result.

  For example: 13 × 22
  
  Step 1: (2 × 100) + 2 + [(2 + 2) × 10] = 242.
  
  Step 2: 22 × 2 = 44.
  
  Answer: 242 + 44 = 286.
  

  If the two digits sum to more than ten, then you carry the one to add it to the number on the left and continue.

  For example: 13 × 65
  
  Step 1: (6 × 100) + 5 + [(6 + 5) × 10] = 715.
  
  Step 2: 65 × 2 = 130.
  
  Answer: 715 + 130 = 845.
  

 Multiplying by sixteen

• Ibrahim Labib offers a quick way to find an answer when multiplying by 16.

  First, multiply the number in question by 10. Then multiply half the number by 10. Then add those two results together with the number itself to get your final answer.

  For example: 16 × 24
  
  Step 1: 24 × 10 = 240
  
  Step 2: (24 × 1/2) × 10 = 12 × 10 = 120
  
  Step 3: add steps 1 and 2 and the number = 240 + 120 + 24 = 384
  
  
  
  For more Tips & Tricks
  visit again
  MATHSCIRCLE

Squaring a 2-digit number beginning

with 1

1. Take a 2-digit number beginning with 1.
2. Square the second digit 
   
   (keep the carry)   _ _ X
   
3. Multiply the second digit by 2 and 
   
   add the carry (keep the carry)   _ X _
   
4. The first digit is one 
   
   (plus the carry)   X _ _
   

   Example:

1. If the number is 16, square the second digit:
   
   6 × 6 = 36   _ _ 6
   
2. Multiply the second digit by 2 and
   
   add the carry: 2 × 6 + 3 = 15   _ 5 _
   
3. The first digit is one plus the carry:
   
   1 + 1 = 2   2 _ _
   
4. So 16 × 16 = 256.

   See the pattern?

1. For 19 × 19, square the second digit:
   
   9 × 9 = 81   _ _ 1
   
2. Multiply the second digit by 2 and
   
   add the carry: 2 × 9 + 8 = 26   _ 6 _
   
3. The first digit is one plus the carry:
   
   1 + 2 = 3   3 _ _
   
4. So 19 × 19 = 361.

Squaring a 2-digit number ending in 3

1. Take a 2-digit number ending in 3.
2. The last digit will be _ _ _ 9.
3. Multiply the first digit by 6: the 2nd number will be 
   
   the next to the last digit: _ _ X 9.
   
4. Square the first digit and add the number carried from 
   
   the previous step: X X _ _.
   

   Example:

1. If the number is 43, the last digit is _ _ _ 9.
2. 6 × 4 = 24 (six times the first digit): _ _ 4 9.
3. 4 × 4 = 16 (square the first digit), 16 + 2 = 18 
   
   (add carry): 1 8 4 9.
   
4. So 43 × 43 = 1849.

   See the pattern?

1. For 83 × 83, the last digit is _ _ _ 9.
2. 6 × 8 = 48 (six times the first digit): _ _ 8 9.
3. 8 × 8 = 64 (square the first digit), 64 + 4 = 68 
   
   (add carry): 6 8 8 9.
   
4. So 83 × 83 = 6889.

Squaring numbers made up of nines

1. Choose a a number made up of nines (up to nine digits).
2. The answer will have one less 9 than the number, one 8, 
   
   the same number of zeros as 9's, and a final 1
   

   Example:

1. If the number to be squared is 9999
2. The square of the number has:

one less nine than the number  9 9 9

one 8                                8

the same number of zeros as 9's        0 0 0

a final 1                                    1

3. So 9999 × 9999 = 99980001.

   See the pattern?

1. If the number to be squared is 999999
2. The square of the number has:

one less nine than the number  9 9 9 9 9

one 8                                   8

the same number of zeros as 9's           0 0 0 0 0

a final 1                                           1

3. So 999999 × 999999 = 999998000001.

This is not a very demanding mental math exercise

if you find any problem in this post please reply me.

for more maths related problem visit again.

MATHSCIRCLE

Magic Numbers (Multiplication Webbing)

Title - Magic Numbers (Multiplication Webbing)
By - Christy Jones
Primary Subject - Math
Secondary Subjects -
Grade Level - 4-5
Objective: Students will apply knowledge of basic multiplication problems to find problems that equal the "magic number."

Materials:
Chalkboard
Scrap paper
Pencil

Procedure:
1. Draw a circle on the board. Draw four lines (about 6 inches) extending from the circle. Draw a rectangle at the end of each extension.

2. Write a number in the circle. This number is the magic number. Example : 6.

3. Ask students to copy the web onto a piece of scrap paper.

4. The students are to think of basic multiplication problems that equal the magic number (6) and fill in the rectangles on their scrap paper. (2x3, 3x2, 6x1, 1x6)

5. Go over the answers as a class.

6. Repeat activity and gradually increase the difficulty level.

Extension:
The teacher may add more rectangles to the web when more possible answers are available. For example: 24.

The teacher may rule out the replication of problems. For example, 2x3 and 3x2 only one of the problems will count in the rectangles.

The activity can be used as a game for speed.

Evaluation:
Did students successfully answer the problems that equal the magic number?

Did students pay attention and copy webs along with class?


This activity also works great with division!!

download vedic maths software for learning easy maths tricks.
http://www.ziddu.com/download/6633986/shortcutvedicmathematic3.rar.html
Mail me if you want more about maths shortcut tricks.
www.mathscircle@Gmail.com

GRE Maths Practic Paper

Download GRE Maths Practic Paper & study hard at home

make your Future strong & safe 

Link:

http://www.ziddu.com/download/6145834/GREmathPractice.pdf.html

Best of Luck