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Problems Archives

The problems archives table shows problems 1 to 726. 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.


ID

Description / TitleSolved By
151Paper sheets of standard sizes: an expected-value problem
5187
152Writing 1/2 as a sum of inverse squares
2488
153Investigating Gaussian Integers
2419
154Exploring Pascal's pyramid
2443
155Counting Capacitor Circuits
3329
156Counting Digits
2244
157Solving the diophantine equation 1/a+1/b= p/10n
2508
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3378
159Digital root sums of factorisations
3075
160Factorial trailing digits
3259
161Triominoes
1942
162Hexadecimal numbers
5050
163Cross-hatched triangles
1664
164Numbers for which no three consecutive digits have a sum greater than a given value
5414
165Intersections
2395
166Criss Cross
3810
167Investigating Ulam sequences
1546
168Number Rotations
2467
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4736
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1828
171Finding numbers for which the sum of the squares of the digits is a square
2561
172Investigating numbers with few repeated digits
3540
173Using up to one million tiles how many different "hollow" square laminae can be formed?
8657
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5537
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1638
176Right-angled triangles that share a cathetus
1755
177Integer angled Quadrilaterals
1169
178Step Numbers
3169
179Consecutive positive divisors
10729
180Rational zeros of a function of three variables
1460
181Investigating in how many ways objects of two different colours can be grouped
1840
182RSA encryption
2440
183Maximum product of parts
4418
184Triangles containing the origin
1505
185Number Mind
2906
186Connectedness of a network
2659
187Semiprimes
10652
188The hyperexponentiation of a number
6061
189Tri-colouring a triangular grid
1899
190Maximising a weighted product
3907
191Prize Strings
6682
192Best Approximations
1470
193Squarefree Numbers
3032
194Coloured Configurations
1279
195Inscribed circles of triangles with one angle of 60 degrees
1274
196Prime triplets
2368
197Investigating the behaviour of a recursively defined sequence
4644
198Ambiguous Numbers
1026
199Iterative Circle Packing
1793
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
2184