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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
251Cardano Triplets
1065
252Convex Holes
657
253Tidying up
803
254Sums of Digit Factorials
752
255Rounded Square Roots
708
256Tatami-Free Rooms
577
257Angular Bisectors
524
258A lagged Fibonacci sequence
1207
259Reachable Numbers
1235
260Stone Game
1039
261Pivotal Square Sums
527
262Mountain Range
566
263An engineers' dream come true
838
264Triangle Centres
459
265Binary Circles
3454
266Pseudo Square Root
1347
267Billionaire
2736
268Counting numbers with at least four distinct prime factors less than 100
1139
269Polynomials with at least one integer root
543
270Cutting Squares
516
271Modular Cubes, part 1
1874
272Modular Cubes, part 2
730
273Sum of Squares
1078
274Divisibility Multipliers
1157
275Balanced Sculptures
481
276Primitive Triangles
855
277A Modified Collatz sequence
2591
278Linear Combinations of Semiprimes
805
279Triangles with integral sides and an integral angle
556
280Ant and seeds
821
281Pizza Toppings
731
282The Ackermann function
769
283Integer sided triangles for which the area/perimeter ratio is integral
527
284Steady Squares
1009
285Pythagorean odds
933
286Scoring probabilities
1698
287Quadtree encoding (a simple compression algorithm)
1129
288An enormous factorial
1282
289Eulerian Cycles
381
290Digital Signature
782
291Panaitopol Primes
1108
292Pythagorean Polygons
467
293Pseudo-Fortunate Numbers
2316
294Sum of digits - experience #23
709
295Lenticular holes
373
296Angular Bisector and Tangent
459
297Zeckendorf Representation
2288
298Selective Amnesia
538
299Three similar triangles
494
300Protein folding
851