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Problems Archives

  • Problem 699 will be accessible in 3 hours, 52 minutes (Sunday, 26th January 2020, 10:00 am)

The problems archives table shows problems 1 to 688. 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
1185
252Convex Holes
721
253Tidying up
894
254Sums of Digit Factorials
818
255Rounded Square Roots
752
256Tatami-Free Rooms
635
257Angular Bisectors
590
258A lagged Fibonacci sequence
1378
259Reachable Numbers
1327
260Stone Game
1147
261Pivotal Square Sums
581
262Mountain Range
616
263An engineers' dream come true
892
264Triangle Centres
496
265Binary Circles
3787
266Pseudo Square Root
1483
267Billionaire
2991
268Counting numbers with at least four distinct prime factors less than 100
1255
269Polynomials with at least one integer root
592
270Cutting Squares
553
271Modular Cubes, part 1
2074
272Modular Cubes, part 2
810
273Sum of Squares
1183
274Divisibility Multipliers
1245
275Balanced Sculptures
528
276Primitive Triangles
934
277A Modified Collatz sequence
2845
278Linear Combinations of Semiprimes
887
279Triangles with integral sides and an integral angle
602
280Ant and seeds
901
281Pizza Toppings
813
282The Ackermann function
852
283Integer sided triangles for which the area/perimeter ratio is integral
566
284Steady Squares
1094
285Pythagorean odds
1045
286Scoring probabilities
1871
287Quadtree encoding (a simple compression algorithm)
1260
288An enormous factorial
1440
289Eulerian Cycles
409
290Digital Signature
858
291Panaitopol Primes
1235
292Pythagorean Polygons
501
293Pseudo-Fortunate Numbers
2591
294Sum of digits - experience #23
796
295Lenticular holes
397
296Angular Bisector and Tangent
505
297Zeckendorf Representation
2482
298Selective Amnesia
585
299Three similar triangles
540
300Protein folding
950