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Problems Archives

The problems archives table shows problems 1 to 670. 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
4783
152Writing 1/2 as a sum of inverse squares
2248
153Investigating Gaussian Integers
2200
154Exploring Pascal's pyramid
2227
155Counting Capacitor Circuits
3071
156Counting Digits
2040
157Solving the diophantine equation 1/a+1/b= p/10n
2275
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3119
159Digital root sums of factorisations
2819
160Factorial trailing digits
2984
161Triominoes
1762
162Hexadecimal numbers
4714
163Cross-hatched triangles
1531
164Numbers for which no three consecutive digits have a sum greater than a given value
5025
165Intersections
2202
166Criss Cross
3499
167Investigating Ulam sequences
1429
168Number Rotations
2268
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4408
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1661
171Finding numbers for which the sum of the squares of the digits is a square
2350
172Investigating numbers with few repeated digits
3266
173Using up to one million tiles how many different "hollow" square laminae can be formed?
8151
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5208
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1512
176Right-angled triangles that share a cathetus
1625
177Integer angled Quadrilaterals
1071
178Step Numbers
2919
179Consecutive positive divisors
10045
180Rational zeros of a function of three variables
1335
181Investigating in how many ways objects of two different colours can be grouped
1698
182RSA encryption
2272
183Maximum product of parts
4126
184Triangles containing the origin
1364
185Number Mind
2684
186Connectedness of a network
2456
187Semiprimes
10014
188The hyperexponentiation of a number
5702
189Tri-colouring a triangular grid
1766
190Maximising a weighted product
3643
191Prize Strings
6262
192Best Approximations
1350
193Squarefree Numbers
2805
194Coloured Configurations
1183
195Inscribed circles of triangles with one angle of 60 degrees
1160
196Prime triplets
2175
197Investigating the behaviour of a recursively defined sequence
4375
198Ambiguous Numbers
945
199Iterative Circle Packing
1632
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
2002