• Puzzles:
• 1-10
• 11-20
• 21-30
• 31-40
• 41-50
• 51-60
• 61-70
• 71-80
• 81-90
• 91-100
• 101-110
• 111-120
• 121-130
• 131-140
• 141-150
• 151-160
• Index
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Index to Nick's Mathematical Puzzles

1. Folded sheet of paper
2. Triangular area
3. Two logicians
4. Equatorial belt
5. Confused bank teller
6. Ant on a box
7. Five men, a monkey, and some coconuts
8. 271
9. Reciprocals and cubes
10. Farmer's enclosure
11. Dice game
12. Making $1
13. Coin triplets
14. Two ladders in an alley
15. Infinite product
16. Zero-sum game
17. Three children
18. One extra coin
19. Five card trick
20. Five card trick, part 2
21. Birthday line
22. Isosceles angle
    • A generalization
23. Length of hypotenuse
24. Die: median throws
25. Die: mean throws
26. Two packs of cards
27. 1000th digit
28. Making 24
29. x^x
30. Two pool balls
31. Area of a rhombus
32. Differentiation conundrum
33. Harmonic sum
34. Harmonic sum 2
35. Cuboids
36. Composite numbers
37. Five marbles
38. Twelve marbles
39. Prime or composite?
40. No consecutive heads
41. Crazy dice
42. Multiplicative sequence
43. Sum of two powers
44. Sum of two powers 2
45. Area of regular 2ⁿ-gon
46. Consecutive subsequence
47. 1000 divisors
48. Exponential equation
49. An odd polynomial
50. Highest score
51. Greatest common divisor
52. Floor function sum
53. The absentminded professor
54. Diophantine squares
55. Area of a trapezoid
56. Partition identity
57. Binomial coefficient divisibility
58. Fifth power plus five
59. Triangle inequality
60. Sum of reciprocals
61. Two cubes?
    • One cube?
62. Four squares on a quadrilateral
63. Cyclic hexagon
64. Balls in an urn
65. Consecutive integer products
66. Quadratic divisibility
67. Random number generator
68. Difference of powers
69. Combinatorial sum
70. One degree
71. Consecutive cubes and squares
72. Depleted harmonic series
73. Unobtuse triangle
74. Sum of 9999 consecutive squares
75. Car journey
76. Square inscribed in a triangle
    • Ladder against a box
77. Minimal straight cut
78. Perfect square
79. Sum of fourth powers
80. Sixes and sevens
81. Digit transfer
82. Consecutive heads
83. Divisibility
84. Missing digits
85. Fibonacci nines
86. Folded card
87. 2004
88. Nested radicals
89. Square digits
90. Powers of 2: rearranged digits
91. Nonagon diagonals
    • Heptagon diagonals
92. Consecutive integer sums
93. Pascal's triangle
94. Square endings
95. Integer polynomial
96. Five real numbers
97. Two squares
98. Three powers
99. Two similar triangles
100. Perpendicular medians
101. Right triangles
102. Almost exponential
103. Root sums
     • Sum of two squares
     • Quadratic roots
104. An arbitrary sum
105. Difference of nth powers
106. Flying cards
107. A mysterious sequence
108. Eyeball to eyeball
109. Nested circular functions
110. Pairwise products
111. Trigonometric progression
     • Six tangents
     • Center of mass
112. Angle bisector
113. Ant in a field
114. Sums of squares and cubes
115. Sum of sines
116. Factorial divisors
     • A generalization
117. Random point in an equilateral triangle
118. Powers of 2: deleted digit
119. Three sines
120. Factorial plus one
121. Integer sequence
122. Powers of 2 and 5
123. Right angle and median
124. The ladder
125. Divisibility by 446617991732222310
126. Intersecting squares
127. Prime number generator
128. Modular equation
129. Abelian group
130. Reciprocal polynomial?
131. Horse race
132. Triangular angle
133. Prime sequence?
134. Sum of reciprocal roots
135. Clock hands
136. Point in a triangle
137. Factorial plus one equals prime power?
138. Integer sum of roots
139. Three towns
140. Six towns
141. Alternating series
142. Sum of two nth powers
143. Semicircle in a triangle
144. Difference of two nth powers
145. Heads and tails
146. Odds and evens
147. Prime or composite 2
148. Power series
149. Ones and nines
150. Isosceles apex angle
151. Painted cubes
152. Totient valence
153. Semicircle in a square
154. Triangle in a trapezoid
155. Sum of two powers is a square?
156. Three simultaneous equations
157. Trigonometric product
158. Fermat squares
159. Eight odd squares
160. Absolute maximum

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Nick Hobson
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