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Problems Archives

The problems archives table shows problems 1 to 661. 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
1125
252Convex Holes
691
253Tidying up
855
254Sums of Digit Factorials
793
255Rounded Square Roots
729
256Tatami-Free Rooms
606
257Angular Bisectors
554
258A lagged Fibonacci sequence
1302
259Reachable Numbers
1294
260Stone Game
1093
261Pivotal Square Sums
555
262Mountain Range
590
263An engineers' dream come true
861
264Triangle Centres
472
265Binary Circles
3644
266Pseudo Square Root
1428
267Billionaire
2861
268Counting numbers with at least four distinct prime factors less than 100
1196
269Polynomials with at least one integer root
562
270Cutting Squares
528
271Modular Cubes, part 1
1977
272Modular Cubes, part 2
765
273Sum of Squares
1124
274Divisibility Multipliers
1211
275Balanced Sculptures
504
276Primitive Triangles
890
277A Modified Collatz sequence
2713
278Linear Combinations of Semiprimes
846
279Triangles with integral sides and an integral angle
575
280Ant and seeds
865
281Pizza Toppings
773
282The Ackermann function
807
283Integer sided triangles for which the area/perimeter ratio is integral
547
284Steady Squares
1055
285Pythagorean odds
988
286Scoring probabilities
1785
287Quadtree encoding (a simple compression algorithm)
1199
288An enormous factorial
1370
289Eulerian Cycles
396
290Digital Signature
825
291Panaitopol Primes
1174
292Pythagorean Polygons
486
293Pseudo-Fortunate Numbers
2455
294Sum of digits - experience #23
760
295Lenticular holes
389
296Angular Bisector and Tangent
485
297Zeckendorf Representation
2378
298Selective Amnesia
567
299Three similar triangles
517
300Protein folding
903