About This Presentation
          This presentation is part of the “Math + Fun!” series devised 
          by Behrooz Parhami, Professor of Computer Engineering at 
          University of California, Santa Barbara. It was first prepared 
          for special lessons in mathematics at Goleta Family School 
          during the 2003-04 and 2004-05 school years. The slides 
          can be used freely in teaching and in other educational 
          settings. Unauthorized uses are strictly prohibited. © 
          Behrooz Parhami
              Edition        Released     Revised       Revised
              First          Apr. 2005
       Apr. 2005                    Number Games                     Slide 2
     What Number Did You Choose?
   1. Pick a number from this list:     1    2    3    4    5    6    7    8    9   10
   2. Multiply the number by 9. If the result has two digits, add the two digits;
       otherwise leave the number alone.
   3. Subtract 5 from the number that you got in step 2.
   4. Pick the letter that corresponds to the number you got in step 3.
     1 = A,  2 = B,  3 = C,  4 = D,  5 = E,  6 = F,  7 = G,  8 = H,  etc.
   5. Pick a country in Europe whose name begins with your letter.
     A = Austria, . . .     B = Belgium, . . .
     C = Croatia, . . .     D = Denmark, . . .
     E = England, . . .     F = France, . . .  etc.
    6. Use the last letter in your country’s name as the first letter of an animal.
    7. Use the last letter of your animal’s name as the first letter of a color.
      Apr. 2005            Number Games             Slide 3
      How Did the Game Work?
   1. Pick a number from this list:     1    2    3    4    5    6    7    8    9   10
   2. Multiply the number by 9.          9  18  27  36  45  54  63  72  81  90
       If the result has two digits, add the two digits      You get 9 in all cases!
   3. Subtract 5 from the number that you got in step 2.     You get 4
   4. Pick the letter that corresponds to the number you got in step 3.
     1 = A,  2 = B,  3 = C,  4 = D,  5 = E,  6 = F,  7 = G,  8 = H,  etc.
   5. Pick a country in Europe whose name begins with your letter.
     A = Austria, . . .      B = Belgium, . . .
     C = Croatia, . . .      D = Denmark, . . .
     E = England, . . .      F = France, . . .     Kangaroo
    6. Use the last letter in your country’s name as the first letter of an animal.
                                                    Orange
    7. Use the last letter of your animal’s name as the first letter of a color.
      Apr. 2005             Number Games              Slide 4
         More Mind-Reading Games
     1.   Think of a 2-digit number (10-99).           You got a 4-digit number that 
     2.   Multiply your number by 5.                   starts with 1, has your original 
     3.   Add 500 to the result of step 2.             2-digit number in the middle, 
     4.   Add the number of your siblings.             and double the number of 
     5.   Double the result of step 4.                 your siblings at the end.
     1.   Think of a number between 1 and 30.
     2.   Tell me in which of the five lists below the number appears.
     List A:    1    3    5    7    9  11  13  15  17  19  21  23  25  27  29     A
     List B:    2    3    6    7  10  11  14  15  18  19  22  23  26  27  30            B
     List C:    4    5    6    7  12  13  14  15  20  21  22  23  28  29  30      C
     List D:    8    9  10  11  12  13  14  15  24  25  26  27  28  29  30              D
     List E:  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30          E E
        Apr. 2005                         Number Games                            Slide 5
             Activity 1: Mind-Reading 
                                 Game
     Play the following mind-reading game with your friends and family
     (First, discover how to tell the number if you know which lists it is in)
    1.  Think of a number between 1 and 20.
    2.  Tell me in which of the five lists below the number appears.
    List A:    1    4    6    8    9  11  14  16  19
    List B:    2    6    7    8  12  17  20
    List C:    3    4    6    9  13  14  18  19  20
    List D:    5    7    8    9  15  16  17  18  19  20
    List E:  10  11  12  13  14  15  16  17  18  19  20
      Challenge: Add a List F to the five lists given above, and complete 
      the lists, so that you can play the game with numbers up to 40.
       Apr. 2005                   Number Games                    Slide 6