Numerical Pastimes 61the result. Or a quite arbitrary sequence of operations maybe used, ending with mUltiplication by some multiple of 9.7. How TO GUESS AN UNKNOWN NUMBER FROM ITS REMAINDERS WHEN DIVIDED BY A SET OF GIVEN NUMBERS.Suppose we use the divisors 4, 5, and 7. Let a, b, and cbe the remainders after division by 4, 5, and 7 respectively.ThenN == 105a + 56b + 120c (modulus = 4·5·7 = 140).In order that the result be unique the number to be guessedshould be required to be less than 140.Note that the coefficient of a, 105, in the expression for Nhas been so chosen that it is exactly divisible by 5 and 7, andgives the remainder 1 when divided by 4. Similarly,56 == 0(m = 4 and m = 7); 56 == 1 (m = 5); and 120 == 0 (m = 4and m = 5); 120 == 1 (m = 7).If the divisors are 3, 5, and 7, and the respective remaindersa, band c, the selected number will beN == 70a+ 21b+ 15cWhen the divisors are 7, 11, and 13,N == 715a + 364b + 924c(m = 105).(m = 1,001).More generally, if p, q, r, ... are prime each to each, anda, b, c, .•. are the respective remainders from these divisors,then nwnbers P, Q. R, ... can be found so thatN == Pa + Qb + Rc + ... (m = pqr . .. ).To find P, form the product qr . •. of all the divisors except p,and select the lowest multiple of this product which leavesthe remainder 1 on division by p. Similarly for Q, R, and soon. The number to be selected should be kept less than theproduct of all the divisors.8. How TO GUESS A NUMBER LESS THAN 1,000. Ask the
62 Mathematical Recreationsperson to divide his number by 42, 48, 56, and 63, and to tellyou the respective remainders, say a, b, c, d. ThenN == 1,008 - (96a + 21b + 90c + 800d) (m = 1,008).To show this, letN = 42p+ a = 48q+ b = 56r+ c = 63s+d. Then96N = 1,008·4p + 96a21N = 1,008·q + 21b90N = 1,008·5r + 90c800N = 1,008·50s+ 800d1,007N = 1,008·S + (96a+ 21b+ 9Oc+ 800d).1,2,3,4,9,10,11,12,17,18,19,20,25,26,27,285,6,7,8,13,14,15,16,21,22,23,24,29,30,31,32t9'£9'C:9'~9'9S'Ill;'K'£9'a.'1.~'~'S~'~'6£'8t'1.£3,7,11,15,19,23,27,31,33,37,41,45,49,63,57,612,6,10,14,18,22,26,30,36,40,44,48,52,56,60,64• • II IIII• •I•,. II•, , , , , , .£9'6S'Ill;' ~S'1.~:£t> 6£ S£ 6i: S<: ~c: L.l £~ 6'S'~<:9'9S'K'OO'~'<:~'Q£'t>£'<:£'9<:'~<:'0 <:'9 ~ 'c: ~ 'g'~13,14,15,16,25,26,27,28,45,46,47,48,57,58,59,609,10,11,12,29,30,31,32,41,42,43,44,61,62,63,64•••••••• ••••9S'9S'K'£9'9£'S£'K'££'~C:'£C:'C:C:'~C:'~'£'C:'••••~c:g' ~ S'OO'6"'~'6£'8t' 1.£'OC:'6 ~ '8 ~ 'L.l'g'1.'9'S1 234 5 6 7 89 10 11 12 13 14 15 1617 18 19 20 21 22 23 2425 26 27 28 29 20 31 3233 34 35 36 37 38 39 4041 42 43 44 45 46 47 4849 50 51 52 53 54 55 5657 58 59 60 61 62 63 64FIGURE 3. Window Reader's Cards for Numbers 1 to 64.
- Page 2 and 3:
MathematicalRecreationsMAURICE KRAI
- Page 4:
TOMR. DANNIE HEINEMANwho encouraged
- Page 7 and 8:
8 Mathematical RecreationsMr. W. W.
- Page 9 and 10: 10 ContentsPAGECHAPTER SEVEN.1. Def
- Page 12 and 13: CHAPTER ONEMATHEMATICS WITHOUT NUMB
- Page 14 and 15: M athematics Without Numbers 15he r
- Page 16 and 17: Mathematic8 without Numbers 17word
- Page 18 and 19: Mathematics witlwut Numbers 19way a
- Page 20 and 21: Mathematics without Numbers 21~ I(h
- Page 22 and 23: Ancient and Curious Problemsto the
- Page 24 and 25: Ancient and Curious Problems 25Any
- Page 26 and 27: Ancient and Curious ProblemsSolutio
- Page 28 and 29: Ancient and Curious Problems 29Semp
- Page 30 and 31: A ncient and Curious Problems 31Ans
- Page 32 and 33: Ancient and Curious Problems 33monk
- Page 34 and 35: SolutionNo.Ancient and Curious Prob
- Page 36 and 37: Ancient and Curiou8 Problemab+da+ci
- Page 38 and 39: Ancient and Curious Problems 89and
- Page 40 and 41: Ancient and Curious Problems 41t =
- Page 42 and 43: thenA ncient and Curious Problemsx-
- Page 44 and 45: Numerical Pastimes 45desired number
- Page 46 and 47: Numerical Pastimes 47Mr. Thebault g
- Page 48 and 49: Numerical Pastimes 49threes I find
- Page 50 and 51: Numerical Pastimes(3) 16ab + c = 16
- Page 52 and 53: Numerical Pastimes 53If the standar
- Page 54 and 55: Numerical Pastimes 55consists of k
- Page 56 and 57: Numerical Pastimes 57sponding to th
- Page 58 and 59: Numerical Pastimes 592. Think of a
- Page 62 and 63: Numerical Pastimes 68If we subtract
- Page 64 and 65: ABCDEFGHIJKLM IIN 0 P Q R STU V W x
- Page 66 and 67: Numerical Pastimes 67progressions.
- Page 68 and 69: Numerical Pastimes 691 (n + d - 2)!
- Page 70 and 71: Numerical Pastimes 71Two or more pr
- Page 72 and 73: Numerical Pastimes 73= 8. m2(m + 1)
- Page 74 and 75: Numerical Pastimes 75Thus, in order
- Page 76 and 77: Numerical Pastimes 778. AUTOMORPHIC
- Page 78 and 79: Numerical Pastimes 79primality has
- Page 80 and 81: Numerical Pastimes 81products with
- Page 82 and 83: Numerical Pastimes 838. QUI)TRO UVE
- Page 84 and 85: Numerical Pastimes 85There are many
- Page 86 and 87: Numerical Pastimes 87if a player A
- Page 88 and 89: Numerical Pastimes 893. CHINESE RIN
- Page 90 and 91: Numerical Pastimes 91rings. If the
- Page 92 and 93: Numerical Pastimes 93others getting
- Page 94 and 95: CHAPTER FOURARITHMETICO-GEOMETRICAL
- Page 96 and 97: SinceArithmetico-Geometrical Questi
- Page 98 and 99: A rithmetico-Geometrical Questions
- Page 100 and 101: Arithmetico-Geometrical Questions 1
- Page 102 and 103: Arithmetico-Geometrical Questions 1
- Page 104 and 105: Arithmetico-Geometrical Questions 1
- Page 106 and 107: Arithmetico-Geometrical Questions 1
- Page 108 and 109: CHAPTER FIVETHE CALENDARTIME can be
- Page 110 and 111:
The Calendar111MONTHMJanua~ .......
- Page 112 and 113:
The Calendar 113scale). For the mon
- Page 114 and 115:
The Calendar 115"other point." In a
- Page 116 and 117:
CHAPTER SIXPROBABILITIESTHE serious
- Page 118 and 119:
Probabilities 119possibilities prod
- Page 120 and 121:
Probabilitiesl~lone suit will not b
- Page 122 and 123:
Probabilities 123into some one of w
- Page 124 and 125:
Probabilities 1~5Finally, the proba
- Page 126 and 127:
Probabilities 127It is clear that t
- Page 128 and 129:
Probabilities 129deck is usually no
- Page 130 and 131:
Probabilitiesunpartments, so that t
- Page 132 and 133:
Probabilities 133from the pieces. T
- Page 134 and 135:
x·whence ~ = S + g.Piwins, we must
- Page 136 and 137:
Probabilities 137with a throw of ta
- Page 138 and 139:
Probabilities 139do. Does there exi
- Page 140 and 141:
Probabilities 141staking .1 of what
- Page 142 and 143:
Magic Squares 143fore we can readil
- Page 144 and 145:
Magic Squares 145change of rows may
- Page 146 and 147:
Magic Squares 147b + h = c + g = d
- Page 148 and 149:
Magic Squares 149fill in the remain
- Page 150 and 151:
Magic Squares 15101-1 -1-1-1-1 "-1-
- Page 152 and 153:
Magic Squares 153in one-, two-, or
- Page 154 and 155:
Magic Squares 155We shall call the
- Page 156 and 157:
Magic Squares 157tinct in the modul
- Page 158 and 159:
Magic Squares 159shows how this met
- Page 160 and 161:
that is,Magic Squaresb+p-Iu+p-1w ==
- Page 162 and 163:
Magic Squares 163semimagic if t, u,
- Page 164 and 165:
Magic Squares 16541, and 14. Hence
- Page 166 and 167:
Magic Squares 167There are no regul
- Page 168 and 169:
Magic Squares 169One can also borde
- Page 170 and 171:
Magic Squares 171element of the giv
- Page 172 and 173:
Magic Squares173113 124 119 126 1 1
- Page 174 and 175:
Magic Squares 175possible to form a
- Page 176 and 177:
Magic Squares 177square of order 12
- Page 178 and 179:
Magic Squares 17912. EULER (GRAECO-
- Page 180 and 181:
Magic Squares 181themselves must th
- Page 182 and 183:
Magic Squares 183Figure 58. If (Fig
- Page 184 and 185:
Magic Squares 185must take. You can
- Page 186 and 187:
Magic Squares 187From this one can
- Page 188 and 189:
Magic Squares 189number of distinct
- Page 190 and 191:
Magic Squares 191We may remark in p
- Page 192 and 193:
CHAPTER EIGHTGEOMETRIC RECREATIONS1
- Page 194 and 195:
Geometric Recreations 1952. Dissect
- Page 196 and 197:
Geometric Recreations 197SoZ1dion:
- Page 198 and 199:
Geometric Recreations 1992. MOSAICS
- Page 200 and 201:
Geometric Recreations~OlMosaic ofMo
- Page 202 and 203:
Geometric Recreations111 1 1 3-+-+-
- Page 204 and 205:
Geometric Recreations ~05have edges
- Page 206 and 207:
Geometric Recreations 207solutions,
- Page 208 and 209:
Geometric Recreations ~09the 20, an
- Page 210 and 211:
Geometric Recreations ~11closed --
- Page 212 and 213:
Geometric Recreations ~13example, s
- Page 214 and 215:
Permutational Problems ~15child, ar
- Page 216 and 217:
Permutational Problems 217the minor
- Page 218 and 219:
Permutational Problems 219The two h
- Page 220 and 221:
Permutational Problems 221Thus it t
- Page 222 and 223:
Permutational ProblemsInitially the
- Page 224 and 225:
Permutational Problemsget onto the
- Page 226 and 227:
Permutational Problemseter give 2n
- Page 228 and 229:
Permutational Problems 229go back t
- Page 230 and 231:
Permutational Problems 231When two
- Page 232 and 233:
Permutational ProblemaRn = nC2 = n(
- Page 234 and 235:
Permutational Problems ~35n = 171,1
- Page 236 and 237:
Permutational Problems 2371,2, 3, 4
- Page 238 and 239:
The Problem of the Queens~391. THE
- Page 240 and 241:
The Problem oj the Queens 241tions.
- Page 242 and 243:
The Problem of the Queens ~43no sol
- Page 244 and 245:
The Problem of the Queens 245Such a
- Page 246 and 247:
The Problem of the Queens 247up int
- Page 248 and 249:
The Problem of the Queens ~49FIGURE
- Page 250 and 251:
The Problem of the Queens 251On the
- Page 252 and 253:
The Problem of the Queens 253n-1 n-
- Page 254 and 255:
The Problem of the Queens '255ular
- Page 256 and 257:
CHAPTER ELEVENTHE PROBLEM OF THE KN
- Page 258 and 259:
The Problem of the KnightU92. W ARN
- Page 260 and 261:
The Problem of the Knight ~61tour i
- Page 262 and 263:
The Problem of the Knight 263tal me
- Page 264 and 265:
The Problem of the Knight265There a
- Page 266 and 267:
CHAPTER TWELVEGAMES1. POSITIONAL GA
- Page 268 and 269:
Games 269The checker man moves one
- Page 270 and 271:
Games 271left," namely" no change."
- Page 272 and 273:
Games 273U- 2 V-1 + u- 2 v + U-1V-2
- Page 274 and 275:
Game8 275(16 moves for the 8 pawns
- Page 276 and 277:
Games 277rules of play, or the piec
- Page 278 and 279:
Games 279The centaur, which combine
- Page 280 and 281:
Games 2816. REVERSI. This is played
- Page 282 and 283:
Games 283tween 2 and 4 balls in eac
- Page 284 and 285:
Games 285This great power granted t
- Page 286 and 287:
Games ~87that White can always win,
- Page 288 and 289:
Games 289if Black), the guide alone
- Page 290 and 291:
Games 291Here are a few games. (W s
- Page 292 and 293:
Games ~98units. The strength of a s
- Page 294 and 295:
Games '295end of the game. When all
- Page 296 and 297:
Games 297first one to be unable to
- Page 298 and 299:
Games 299draw. In case of tie the o
- Page 300 and 301:
Games 301in the original game, exce
- Page 302 and 303:
Games 303initially the cubes are se
- Page 304 and 305:
Games 805aspects of the theory of p
- Page 306 and 307:
Games 307n (> 1) objects are even,
- Page 308 and 309:
Games 309the two sets of pawns inte
- Page 310 and 311:
Games 311Grasshopper is a variant o
- Page 312 and 313:
Games 313one tries to construct squ
- Page 314 and 315:
Games 315umn, one takes that opport
- Page 316 and 317:
GamesRl Bl ~ B2 R3 B3 ~ B4~ B3 Rl B
- Page 318 and 319:
Games 319cards by pairs in order an
- Page 320 and 321:
Games 321up after the fifth deal in
- Page 322 and 323:
Games 3~3of the cuts, we find that
- Page 324 and 325:
THE FALSE COIN. 825Hence we can ide
- Page 326 and 327:
Index 827Composite magic squares, 1
- Page 328 and 329:
Needle problem, 132Negative digits,