Mathematical_Recreations-Kraitchik-2e

64 Mathematical Recreations
In Figure 4 is given a set of six cards for use in determining
a number up to 20. In this case each number appears on
three of the cards. A similar set of eight cards can be devised
for numbers up to 70.
1~ 2, 3,
4,5,6,
9, 10
II
I
..
II
•
9l 'Sl
'.,l '£l 'cH
U '8 'lo
1,4, 5,
8, 10, 11,
14, 15
•
•
•
•
•
9~ '£l
'ea '6 'lo
'9 '£ '~
1,2,6,
8, 10, 12
13, 14
5,6, 9,
10, 13, 14
15, 16
•
• •
•
II
..
•
,.
.. •
9~ 'Sl
'u '6 'lo
's '., '£
II
II
II
ca 'u
'8 'lo '.,
'£ 'e: 'I.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
FIGURE 5. Window Reader's Cards for Numbers 1 to 16.
For numbers up to 16 the set of four cards in Figure 5 may
be used.
To guess a letter of the alphabet, either seven or eight
window cards and a master card may be used, respectively
as in Figures 6 and 7. In the case of Figure 7, the window
reader specifies the use of the cards which do not contain the
given letter.