Cache update: 45 minutes

Problems Archives

  • Problem 727 will be accessible in 11 hours, 21 minutes (Saturday, 26th September 2020, 11:00 pm)

The problems archives table shows problems 1 to 716. 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.


ID

Description / TitleSolved By
151Paper sheets of standard sizes: an expected-value problem
5148
152Writing 1/2 as a sum of inverse squares
2458
153Investigating Gaussian Integers
2391
154Exploring Pascal's pyramid
2422
155Counting Capacitor Circuits
3291
156Counting Digits
2213
157Solving the diophantine equation 1/a+1/b= p/10n
2474
158Exploring strings for which only one character comes lexicographically after its neighbour to the left
3348
159Digital root sums of factorisations
3038
160Factorial trailing digits
3224
161Triominoes
1915
162Hexadecimal numbers
5006
163Cross-hatched triangles
1647
164Numbers for which no three consecutive digits have a sum greater than a given value
5367
165Intersections
2374
166Criss Cross
3768
167Investigating Ulam sequences
1534
168Number Rotations
2434
169Exploring the number of different ways a number can be expressed as a sum of powers of 2
4689
170Find the largest 0 to 9 pandigital that can be formed by concatenating products
1813
171Finding numbers for which the sum of the squares of the digits is a square
2539
172Investigating numbers with few repeated digits
3505
173Using up to one million tiles how many different "hollow" square laminae can be formed?
8606
174Counting the number of "hollow" square laminae that can form one, two, three, ... distinct arrangements
5502
175Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
1619
176Right-angled triangles that share a cathetus
1733
177Integer angled Quadrilaterals
1158
178Step Numbers
3140
179Consecutive positive divisors
10654
180Rational zeros of a function of three variables
1445
181Investigating in how many ways objects of two different colours can be grouped
1815
182RSA encryption
2418
183Maximum product of parts
4380
184Triangles containing the origin
1486
185Number Mind
2882
186Connectedness of a network
2636
187Semiprimes
10574
188The hyperexponentiation of a number
6021
189Tri-colouring a triangular grid
1881
190Maximising a weighted product
3870
191Prize Strings
6632
192Best Approximations
1453
193Squarefree Numbers
3011
194Coloured Configurations
1268
195Inscribed circles of triangles with one angle of 60 degrees
1259
196Prime triplets
2344
197Investigating the behaviour of a recursively defined sequence
4607
198Ambiguous Numbers
1013
199Iterative Circle Packing
1763
200Find the 200th prime-proof sqube containing the contiguous sub-string "200"
2160