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Problems Archives

The problems archives table shows problems 1 to 652. 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
4626
152Writing 1/2 as a sum of inverse squares
2154
153Investigating Gaussian Integers
2114
154Exploring Pascal's pyramid
2152
155Counting Capacitor Circuits
2961
156Counting Digits
1953
157Solving the diophantine equation 1/a+1/b= p/10n
2192
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3015
159Digital root sums of factorisations
2722
160Factorial trailing digits
2871
161Triominoes
1689
162Hexadecimal numbers
4581
163Cross-hatched triangles
1478
164Numbers for which no three consecutive digits have a sum greater than a given value
4866
165Intersections
2132
166Criss Cross
3391
167Investigating Ulam sequences
1373
168Number Rotations
2190
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4283
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1598
171Finding numbers for which the sum of the squares of the digits is a square
2260
172Investigating numbers with few repeated digits
3167
173Using up to one million tiles how many different "hollow" square laminae can be formed?
7908
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5054
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1462
176Right-angled triangles that share a cathetus
1565
177Integer angled Quadrilaterals
1021
178Step Numbers
2799
179Consecutive positive divisors
9743
180Rational zeros of a function of three variables
1274
181Investigating in how many ways objects of two different colours can be grouped
1634
182RSA encryption
2180
183Maximum product of parts
4008
184Triangles containing the origin
1305
185Number Mind
2603
186Connectedness of a network
2376
187Semiprimes
9729
188The hyperexponentiation of a number
5559
189Tri-colouring a triangular grid
1696
190Maximising a weighted product
3540
191Prize Strings
6084
192Best Approximations
1293
193Squarefree Numbers
2714
194Coloured Configurations
1124
195Inscribed circles of triangles with one angle of 60 degrees
1104
196Prime triplets
2102
197Investigating the behaviour of a recursively defined sequence
4264
198Ambiguous Numbers
893
199Iterative Circle Packing
1565
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
1922