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Problems Archives

The problems archives table shows problems 1 to 751. 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
5353
152Writing 1/2 as a sum of inverse squares
2573
153Investigating Gaussian Integers
2509
154Exploring Pascal's pyramid
2536
155Counting Capacitor Circuits
3453
156Counting Digits
2309
157Solving the diophantine equation 1/a+1/b= p/10n
2597
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3489
159Digital root sums of factorisations
3178
160Factorial trailing digits
3373
161Triominoes
2015
162Hexadecimal numbers
5196
163Cross-hatched triangles
1731
164Numbers for which no three consecutive digits have a sum greater than a given value
5575
165Intersections
2484
166Criss Cross
3951
167Investigating Ulam sequences
1599
168Number Rotations
2556
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4878
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1892
171Finding numbers for which the sum of the squares of the digits is a square
2650
172Investigating numbers with few repeated digits
3651
173Using up to one million tiles how many different "hollow" square laminae can be formed?
8861
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5672
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1693
176Right-angled triangles that share a cathetus
1812
177Integer angled Quadrilaterals
1212
178Step Numbers
3276
179Consecutive positive divisors
10994
180Rational zeros of a function of three variables
1502
181Investigating in how many ways objects of two different colours can be grouped
1889
182RSA encryption
2508
183Maximum product of parts
4533
184Triangles containing the origin
1556
185Number Mind
2997
186Connectedness of a network
2731
187Semiprimes
10913
188The hyperexponentiation of a number
6213
189Tri-colouring a triangular grid
1959
190Maximising a weighted product
4011
191Prize Strings
6864
192Best Approximations
1514
193Squarefree Numbers
3179
194Coloured Configurations
1321
195Inscribed circles of triangles with one angle of 60 degrees
1315
196Prime triplets
2462
197Investigating the behaviour of a recursively defined sequence
4753
198Ambiguous Numbers
1051
199Iterative Circle Packing
1856
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
2254