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Problems


ID Description / Title
151
 Paper sheets of standard sizes: an expected-value problem
152
 Writing 1/2 as a sum of inverse squares
153
 Investigating Gaussian Integers
154
 Exploring Pascal's pyramid
155
 Counting Capacitor Circuits
156
 Counting Digits
157
 Solving the diophantine equation 1/a+1/b= p/10n
158
 Exploring strings for which only one character comes lexicographically after its neighbour to the left
159
 Digital root sums of factorisations
160
 Factorial trailing digits
161
 Triominoes
162
 Hexadecimal numbers
163
 Cross-hatched triangles
164
 Numbers for which no three consecutive digits have a sum greater than a given value
165
 Intersections
166
 Criss Cross
167
 Investigating Ulam sequences
168
 Number Rotations
169
 Exploring the number of different ways a number can be expressed as a sum of powers of 2
170
 Find the largest 0 to 9 pandigital that can be formed by concatenating products
171
 Finding numbers for which the sum of the squares of the digits is a square
172
 Investigating numbers with few repeated digits
173
 Using up to one million tiles how many different "hollow" square laminae can be formed?
174
 Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
175
 Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
176
 Right-angled triangles that share a cathetus
177
 Integer angled Quadrilaterals
178
 Step Numbers
179
 Consecutive positive divisors
180
 Rational zeros of a function of three variables
181
 Investigating in how many ways objects of two different colours can be grouped
182
 RSA encryption
183
 Maximum product of parts
184
 Triangles containing the origin
185
 Number Mind
186
 Connectedness of a network
187
 Semiprimes
188
 The hyperexponentiation of a number
189
 Tri-colouring a triangular grid
190
 Maximising a weighted product
191
 Prize Strings
192
 Best Approximations
193
 Squarefree Numbers
194
 Coloured Configurations
195
 Inscribed circles of triangles with one angle of 60 degrees
196
 Prime triplets
197
 Investigating the behaviour of a recursively defined sequence
198
 Ambiguous Numbers
199
 Iterative Circle Packing
200
 Find the 200th prime-proof sqube containing the contiguous sub-string "200"