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Problems Archives

The problems archives table shows problems 1 to 713. 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
5074
152Writing 1/2 as a sum of inverse squares
2419
153Investigating Gaussian Integers
2350
154Exploring Pascal's pyramid
2384
155Counting Capacitor Circuits
3247
156Counting Digits
2181
157Solving the diophantine equation 1/a+1/b= p/10n
2435
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3307
159Digital root sums of factorisations
2991
160Factorial trailing digits
3170
161Triominoes
1888
162Hexadecimal numbers
4948
163Cross-hatched triangles
1622
164Numbers for which no three consecutive digits have a sum greater than a given value
5297
165Intersections
2338
166Criss Cross
3709
167Investigating Ulam sequences
1505
168Number Rotations
2397
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4636
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1783
171Finding numbers for which the sum of the squares of the digits is a square
2492
172Investigating numbers with few repeated digits
3454
173Using up to one million tiles how many different "hollow" square laminae can be formed?
8530
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5433
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1592
176Right-angled triangles that share a cathetus
1706
177Integer angled Quadrilaterals
1133
178Step Numbers
3089
179Consecutive positive divisors
10538
180Rational zeros of a function of three variables
1424
181Investigating in how many ways objects of two different colours can be grouped
1790
182RSA encryption
2389
183Maximum product of parts
4331
184Triangles containing the origin
1460
185Number Mind
2851
186Connectedness of a network
2603
187Semiprimes
10461
188The hyperexponentiation of a number
5956
189Tri-colouring a triangular grid
1853
190Maximising a weighted product
3824
191Prize Strings
6568
192Best Approximations
1427
193Squarefree Numbers
2969
194Coloured Configurations
1244
195Inscribed circles of triangles with one angle of 60 degrees
1235
196Prime triplets
2305
197Investigating the behaviour of a recursively defined sequence
4550
198Ambiguous Numbers
995
199Iterative Circle Packing
1731
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
2117