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Problems Archives

The problems archives table shows problems 1 to 621. 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
4411
152Writing 1/2 as a sum of inverse squares
2046
153Investigating Gaussian Integers
2024
154Exploring Pascal's pyramid
2065
155Counting Capacitor Circuits
2826
156Counting Digits
1859
157Solving the diophantine equation 1/a+1/b= p/10n
2098
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
2885
159Digital root sums of factorisations
2619
160Factorial trailing digits
2750
161Triominoes
1620
162Hexadecimal numbers
4412
163Cross-hatched triangles
1421
164Numbers for which no three consecutive digits have a sum greater than a given value
4660
165Intersections
2035
166Criss Cross
3262
167Investigating Ulam sequences
1325
168Number Rotations
2095
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4089
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1536
171Finding numbers for which the sum of the squares of the digits is a square
2171
172Investigating numbers with few repeated digits
3039
173Using up to one million tiles how many different "hollow" square laminae can be formed?
7586
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
4851
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1405
176Right-angled triangles that share a cathetus
1505
177Integer angled Quadrilaterals
975
178Step Numbers
2701
179Consecutive positive divisors
9397
180Rational zeros of a function of three variables
1219
181Investigating in how many ways objects of two different colours can be grouped
1583
182RSA encryption
2068
183Maximum product of parts
3853
184Triangles containing the origin
1251
185Number Mind
2491
186Connectedness of a network
2273
187Semiprimes
9359
188The hyperexponentiation of a number
5339
189Tri-colouring a triangular grid
1635
190Maximising a weighted product
3398
191Prize Strings
5855
192Best Approximations
1238
193Squarefree Numbers
2598
194Coloured Configurations
1087
195Inscribed circles of triangles with one angle of 60 degrees
1054
196Prime triplets
2017
197Investigating the behaviour of a recursively defined sequence
4126
198Ambiguous Numbers
855
199Iterative Circle Packing
1502
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
1845