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Problems Archives

The problems archives table shows problems 1 to 751. 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
551Sum of digits sequence
436
552Chinese leftovers II
400
553Power sets of power sets
199
554Centaurs on a chess board
212
555McCarthy 91 function
644
556Squarefree Gaussian Integers
223
557Cutting triangles
268
558Irrational base
230
559Permuted Matrices
174
560Coprime Nim
277
561Divisor Pairs
692
562Maximal perimeter
173
563Robot Welders
303
564Maximal polygons
217
565Divisibility of sum of divisors
565
566Cake Icing Puzzle
147
567Reciprocal games I
258
568Reciprocal games II
250
569Prime Mountain Range
367
570Snowflakes
253
571Super Pandigital Numbers
1013
572Idempotent matrices
308
573Unfair race
183
574Verifying Primes
242
575Wandering Robots
536
576Irrational jumps
214
577Counting hexagons
1451
578Integers with decreasing prime powers
209
579Lattice points in lattice cubes
141
580Squarefree Hilbert numbers
220
58147-smooth triangular numbers
778
582Nearly isosceles 120 degree triangles
297
583Heron Envelopes
347
584Birthday Problem Revisited
175
585Nested square roots
159
586Binary Quadratic Form
200
587Concave triangle
2874
588Quintinomial coefficients
394
589Poohsticks Marathon
173
590Sets with a given Least Common Multiple
241
591Best Approximations by Quadratic Integers
172
592Factorial trailing digits 2
262
593Fleeting Medians
500
594Rhombus Tilings
171
595Incremental Random Sort
571
596Number of lattice points in a hyperball
331
597Torpids
148
598Split Divisibilities
448
599Distinct Colourings of a Rubik's Cube
275
600Integer sided equiangular hexagons
564