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Problems Archives

The problems archives table shows problems 1 to 699. 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
551Sum of digits sequence
392
552Chinese leftovers II
353
553Power sets of power sets
174
554Centaurs on a chess board
181
555McCarthy 91 function
580
556Squarefree Gaussian Integers
191
557Cutting triangles
242
558Irrational base
200
559Permuted Matrices
149
560Coprime Nim
244
561Divisor Pairs
632
562Maximal perimeter
157
563Robot Welders
271
564Maximal polygons
201
565Divisibility of sum of divisors
511
566Cake Icing Puzzle
123
567Reciprocal games I
229
568Reciprocal games II
220
569Prime Mountain Range
333
570Snowflakes
233
571Super Pandigital Numbers
899
572Idempotent matrices
277
573Unfair race
167
574Verifying Primes
224
575Wandering Robots
465
576Irrational jumps
190
577Counting hexagons
1299
578Integers with decreasing prime powers
184
579Lattice points in lattice cubes
123
580Squarefree Hilbert numbers
197
58147-smooth triangular numbers
691
582Nearly isosceles 120 degree triangles
265
583Heron Envelopes
312
584Birthday Problem Revisited
150
585Nested square roots
129
586Binary Quadratic Form
182
587Concave triangle
2538
588Quintinomial coefficients
355
589Poohsticks Marathon
154
590Sets with a given Least Common Multiple
212
591Best Approximations by Quadratic Integers
154
592Factorial trailing digits 2
235
593Fleeting Medians
439
594Rhombus Tilings
157
595Incremental Random Sort
522
596Number of lattice points in a hyperball
293
597Torpids
123
598Split Divisibilities
400
599Distinct Colourings of a Rubik's Cube
241
600Integer sided equiangular hexagons
500