Cache update: 53 minutes

Problems Archives

  • Problem 699 will be accessible in 4 hours, 46 minutes (Sunday, 26th January 2020, 10:00 am)

The problems archives table shows problems 1 to 688. 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
4917
152Writing 1/2 as a sum of inverse squares
2329
153Investigating Gaussian Integers
2271
154Exploring Pascal's pyramid
2298
155Counting Capacitor Circuits
3140
156Counting Digits
2102
157Solving the diophantine equation 1/a+1/b= p/10n
2326
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3188
159Digital root sums of factorisations
2885
160Factorial trailing digits
3043
161Triominoes
1808
162Hexadecimal numbers
4803
163Cross-hatched triangles
1563
164Numbers for which no three consecutive digits have a sum greater than a given value
5122
165Intersections
2252
166Criss Cross
3577
167Investigating Ulam sequences
1453
168Number Rotations
2322
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4502
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1711
171Finding numbers for which the sum of the squares of the digits is a square
2405
172Investigating numbers with few repeated digits
3335
173Using up to one million tiles how many different "hollow" square laminae can be formed?
8294
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5292
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1544
176Right-angled triangles that share a cathetus
1662
177Integer angled Quadrilaterals
1093
178Step Numbers
2983
179Consecutive positive divisors
10225
180Rational zeros of a function of three variables
1376
181Investigating in how many ways objects of two different colours can be grouped
1746
182RSA encryption
2322
183Maximum product of parts
4216
184Triangles containing the origin
1409
185Number Mind
2747
186Connectedness of a network
2515
187Semiprimes
10185
188The hyperexponentiation of a number
5794
189Tri-colouring a triangular grid
1807
190Maximising a weighted product
3724
191Prize Strings
6378
192Best Approximations
1382
193Squarefree Numbers
2873
194Coloured Configurations
1212
195Inscribed circles of triangles with one angle of 60 degrees
1190
196Prime triplets
2232
197Investigating the behaviour of a recursively defined sequence
4456
198Ambiguous Numbers
965
199Iterative Circle Packing
1678
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
2048