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Problems Archives

The problems archives table shows problems 1 to 617. If you would like to tackle the 10 most recently published problems then go to Recent problems.
Click the description/title of the problem to view details and submit your answer.


IDDescription / TitleSolved By
151Paper sheets of standard sizes: an expected-value problem
4370
152Writing 1/2 as a sum of inverse squares
2039
153Investigating Gaussian Integers
2010
154Exploring Pascal's pyramid
2049
155Counting Capacitor Circuits
2819
156Counting Digits
1846
157Solving the diophantine equation 1/a+1/b= p/10n
2088
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
2873
159Digital root sums of factorisations
2592
160Factorial trailing digits
2734
161Triominoes
1615
162Hexadecimal numbers
4388
163Cross-hatched triangles
1417
164Numbers for which no three consecutive digits have a sum greater than a given value
4623
165Intersections
2019
166Criss Cross
3239
167Investigating Ulam sequences
1319
168Number Rotations
2080
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4060
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1526
171Finding numbers for which the sum of the squares of the digits is a square
2162
172Investigating numbers with few repeated digits
3024
173Using up to one million tiles how many different "hollow" square laminae can be formed?
7525
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
4824
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1399
176Right-angled triangles that share a cathetus
1499
177Integer angled Quadrilaterals
965
178Step Numbers
2683
179Consecutive positive divisors
9331
180Rational zeros of a function of three variables
1216
181Investigating in how many ways objects of two different colours can be grouped
1573
182RSA encryption
2061
183Maximum product of parts
3820
184Triangles containing the origin
1247
185Number Mind
2472
186Connectedness of a network
2266
187Semiprimes
9285
188The hyperexponentiation of a number
5297
189Tri-colouring a triangular grid
1625
190Maximising a weighted product
3380
191Prize Strings
5831
192Best Approximations
1232
193Squarefree Numbers
2590
194Coloured Configurations
1084
195Inscribed circles of triangles with one angle of 60 degrees
1039
196Prime triplets
2008
197Investigating the behaviour of a recursively defined sequence
4103
198Ambiguous Numbers
850
199Iterative Circle Packing
1498
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
1833