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Problems Archives

The problems archives table shows problems 1 to 726. 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
51Prime digit replacements
33025
52Permuted multiples
64348
53Combinatoric selections
58100
54Poker hands
35298
55Lychrel numbers
52943
56Powerful digit sum
57354
57Square root convergents
40763
58Spiral primes
39364
59XOR decryption
40416
60Prime pair sets
25879
61Cyclical figurate numbers
24725
62Cubic permutations
30616
63Powerful digit counts
42356
64Odd period square roots
21443
65Convergents of e
29138
66Diophantine equation
18999
67Maximum path sum II
94892
68Magic 5-gon ring
20091
69Totient maximum
33938
70Totient permutation
21589
71Ordered fractions
28530
72Counting fractions
21671
73Counting fractions in a range
24341
74Digit factorial chains
26017
75Singular integer right triangles
17344
76Counting summations
27861
77Prime summations
18509
78Coin partitions
16238
79Passcode derivation
40252
80Square root digital expansion
19199
81Path sum: two ways
33546
82Path sum: three ways
20474
83Path sum: four ways
17551
84Monopoly odds
12106
85Counting rectangles
23985
86Cuboid route
12182
87Prime power triples
20235
88Product-sum numbers
9601
89Roman numerals
20578
90Cube digit pairs
10737
91Right triangles with integer coordinates
14870
92Square digit chains
40720
93Arithmetic expressions
11259
94Almost equilateral triangles
11777
95Amicable chains
13703
96Su Doku
16500
97Large non-Mersenne prime
42433
98Anagramic squares
10830
99Largest exponential
29757
100Arranged probability
15667