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Problems Archives

The problems archives table shows problems 1 to 632. 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
4506
152Writing 1/2 as a sum of inverse squares
2092
153Investigating Gaussian Integers
2062
154Exploring Pascal's pyramid
2093
155Counting Capacitor Circuits
2883
156Counting Digits
1886
157Solving the diophantine equation 1/a+1/b= p/10n
2140
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
2949
159Digital root sums of factorisations
2660
160Factorial trailing digits
2800
161Triominoes
1648
162Hexadecimal numbers
4497
163Cross-hatched triangles
1438
164Numbers for which no three consecutive digits have a sum greater than a given value
4744
165Intersections
2067
166Criss Cross
3312
167Investigating Ulam sequences
1347
168Number Rotations
2130
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4177
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1561
171Finding numbers for which the sum of the squares of the digits is a square
2204
172Investigating numbers with few repeated digits
3105
173Using up to one million tiles how many different "hollow" square laminae can be formed?
7738
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
4949
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1428
176Right-angled triangles that share a cathetus
1532
177Integer angled Quadrilaterals
994
178Step Numbers
2745
179Consecutive positive divisors
9554
180Rational zeros of a function of three variables
1246
181Investigating in how many ways objects of two different colours can be grouped
1604
182RSA encryption
2134
183Maximum product of parts
3926
184Triangles containing the origin
1274
185Number Mind
2542
186Connectedness of a network
2318
187Semiprimes
9545
188The hyperexponentiation of a number
5450
189Tri-colouring a triangular grid
1660
190Maximising a weighted product
3466
191Prize Strings
5955
192Best Approximations
1261
193Squarefree Numbers
2657
194Coloured Configurations
1103
195Inscribed circles of triangles with one angle of 60 degrees
1075
196Prime triplets
2046
197Investigating the behaviour of a recursively defined sequence
4191
198Ambiguous Numbers
871
199Iterative Circle Packing
1528
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
1874