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Problems Archives

The problems archives table shows problems 1 to 679. 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
4839
152Writing 1/2 as a sum of inverse squares
2281
153Investigating Gaussian Integers
2233
154Exploring Pascal's pyramid
2256
155Counting Capacitor Circuits
3103
156Counting Digits
2074
157Solving the diophantine equation 1/a+1/b= p/10n
2291
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3146
159Digital root sums of factorisations
2843
160Factorial trailing digits
3015
161Triominoes
1778
162Hexadecimal numbers
4751
163Cross-hatched triangles
1546
164Numbers for which no three consecutive digits have a sum greater than a given value
5078
165Intersections
2223
166Criss Cross
3535
167Investigating Ulam sequences
1440
168Number Rotations
2294
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4455
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1685
171Finding numbers for which the sum of the squares of the digits is a square
2379
172Investigating numbers with few repeated digits
3293
173Using up to one million tiles how many different "hollow" square laminae can be formed?
8211
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5241
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1528
176Right-angled triangles that share a cathetus
1643
177Integer angled Quadrilaterals
1083
178Step Numbers
2946
179Consecutive positive divisors
10120
180Rational zeros of a function of three variables
1352
181Investigating in how many ways objects of two different colours can be grouped
1719
182RSA encryption
2297
183Maximum product of parts
4174
184Triangles containing the origin
1388
185Number Mind
2711
186Connectedness of a network
2483
187Semiprimes
10073
188The hyperexponentiation of a number
5740
189Tri-colouring a triangular grid
1787
190Maximising a weighted product
3685
191Prize Strings
6308
192Best Approximations
1366
193Squarefree Numbers
2837
194Coloured Configurations
1195
195Inscribed circles of triangles with one angle of 60 degrees
1174
196Prime triplets
2200
197Investigating the behaviour of a recursively defined sequence
4410
198Ambiguous Numbers
953
199Iterative Circle Packing
1649
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
2023