Math

Hotel Room, Bellboy and the Missing Dollar

3 men go into a hotel. The man behind the desk says a room is $30 so each man pays $10 and goes to the room.


A while later the man behind the desk realized the room was only $25 so he sent the bellboy to the 3 guys' room with $5. On the way the bellboy couldn't figure out how to split $5 evenly between 3 men, so he gave each man a $1 and kept the other $2 for himself.


This meant that the 3 men each paid $9 for the room, which is a total of $27 add the $2 that the bellboy kept = $29. Where is the other dollar?


The short answer:

There is no missing dollar. The men spent $27. Of which $25 went on the room and $2 went to the light fingered bell boy. You can not add the $2 the bellboy has to the $27 the men spent as this $2 actually comes out of the $27 the men spent, the other $25 going on the room.


Put another way consider how the $30 breaks down:

● $25 — room
● $3 (3x $1) — back to the men
● $2 — Bellboy


How To Convert Fahrenheit to Celsius

Celsius to Fahrenheit

Multiply the temperature by 2 and then add 30 (actual formula is multiply by 1.8, add 32)


Fahrenheit to Celsius

Now just work it backwards, subtract 30 from the temperature and then divide by 2



How To Read Someone's Mind Using Math

  1. Think of a number between 1 and 10.
  2. Multiply this number by 9.
  3. You've got a two-digit number, add the first and second digits together.
  4. Subtract 5.
  5. Now, look through the alphabet to find the letter which corresponds to your number.
  6. Now, think of an european country that begins with that letter.
  7. Using the second letter of the country's name, think of a big animal that begins with that letter.


Didn't you know that there are no elephants in denmark ?


1 = A
2 = B 
3 = C 
4 = D 
5 = E 
6 = F  
7 = G  
8 = H  
9 = I  
10 = J  
11 = K  
12 = L  
13 = M  
14 = N  
15 = O  
16 = P  
17 = Q  
18 = R  
19 = S  
20 = T  
21 = U  
22 = V  
23 = W  
24 = X  
25 = Y  
26 = Z


Names For Large Numbers

1 = 个 = One

10 = 十 = Ten

100 = 百 = Hundred

1,000 = 千 = Thousand

10,000 = 万 = Ten Thousand

100,000 = 十万 = One Hundred Thousand

1,000,000 = 百万 = One Million

10,000,000 = 千万 = Ten Million

100,000,000 = 亿 = One Hundred Million

1,000,000,000 = 十亿 = One Billion

10,000,000,000 = 百亿 = Ten Billion

100,000,000,000 = 千亿 = One Hundred Billion

1,000,000,000,000 = 一兆 = One Trillion

10,000,000,000,000,000 = 一京 = Ten Quadrillion

100,000,000,000,000,000,000 = 一垓 = One Hundred Quintillion



Psychic Mathematics

  1. Choose any one-digit or two-digit number.
  2. Multiply it by 2.
  3. Add 12.
  4. Divide the new number by 2.
  5. Subtract the original number from the remainder.


You're thinking about the number 6, right ?


Roman Number

1 - I

2 - II

3 - III

4 - IV

5 - V

6 - VI

7 - VII

8 - VIII

9 - IX

10 - X

11 - XI

12 - XII

13 - XIII

14 - XIV

15 - XV

16 - XVI

17 - XVII

18 - XVIII

19 - XIX

20 - XX

30 - XXX

40 - XL

50 - L

60 - LX

70 - LXX

80 - LXXX

90 - XC

100 - C

200 - CC

300 - CCC

400 - CD

500 - D

600 - DC

700 - DCC

800 - DCCC

900 - CM

1000 - M

5000 - V

10000 - X

50000 - L

100000 - C

500000 - D

1000000 - M



The Beauty Of Numbers

        1 x 8 + 1 = 9
       12 x 8 + 2 = 98
      123 x 8 + 3 = 987
     1234 x 8 + 4 = 9876
    12345 x 8 + 5 = 98765
   123456 x 8 + 6 = 987654
  1234567 x 8 + 7 = 9876543
 12345678 x 8 + 8 = 98765432
123456789 x 8 + 9 = 987654321


         1 x 9 + 2 = 11
        12 x 9 + 3 = 111
       123 x 9 + 4 = 1111
      1234 x 9 + 5 = 11111
     12345 x 9 + 6 = 111111
    123456 x 9 + 7 = 1111111
   1234567 x 9 + 8 = 11111111
  12345678 x 9 + 9 = 111111111
123456789 x 9 + 10 = 1111111111


        9 x 9 + 7 = 88
       98 x 9 + 6 = 888
      987 x 9 + 5 = 8888
     9876 x 9 + 4 = 88888
    98765 x 9 + 3 = 888888
   987654 x 9 + 2 = 8888888
  9876543 x 9 + 1 = 88888888
 98765432 x 9 + 0 = 888888888
987654321 x 9 - 1 = 8888888888


                1 x 1 = 1
              11 x 11 = 121
            111 x 111 = 12321
          1111 x 1111 = 1234321
        11111 x 11111 = 123454321
      111111 x 111111 = 12345654321
    1111111 x 1111111 = 1234567654321
  11111111 x 11111111 = 123456787654321
111111111 x 111111111 = 12345678987654321


Tic Tac Toe

  1. If you are the first, put your first move at any one of the corner.
  2. If your enemy don't put at the middle, 100% you will win the game.
  3. Enemy's Move(2 / 4 / 6 / 8) - Put your second move at the corner which opposite your enemy's move and opposite your first move.
  4. Enemy's Move(1 / 3 / 5 / 7) - Put your second move at the corner which opposite your enemy's move and no opposite your first move.


Tips: If you are the second, just put your move at the middle to let the game tie.