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Problems Archives

The problems archives table shows problems 1 to 679. 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
51Prime digit replacements
30505
52Permuted multiples
60201
53Combinatoric selections
54325
54Poker hands
32705
55Lychrel numbers
49489
56Powerful digit sum
53672
57Square root convergents
37870
58Spiral primes
36652
59XOR decryption
37973
60Prime pair sets
23899
61Cyclical figurate numbers
22964
62Cubic permutations
28389
63Powerful digit counts
39446
64Odd period square roots
19892
65Convergents of e
27209
66Diophantine equation
17658
67Maximum path sum II
89384
68Magic 5-gon ring
18653
69Totient maximum
31454
70Totient permutation
20072
71Ordered fractions
26534
72Counting fractions
20126
73Counting fractions in a range
22775
74Digit factorial chains
24248
75Singular integer right triangles
16098
76Counting summations
26034
77Prime summations
17152
78Coin partitions
15053
79Passcode derivation
38177
80Square root digital expansion
17905
81Path sum: two ways
31527
82Path sum: three ways
19149
83Path sum: four ways
16357
84Monopoly odds
11256
85Counting rectangles
22455
86Cuboid route
11294
87Prime power triples
18870
88Product-sum numbers
8824
89Roman numerals
19379
90Cube digit pairs
9941
91Right triangles with integer coordinates
13846
92Square digit chains
38313
93Arithmetic expressions
10411
94Almost equilateral triangles
10895
95Amicable chains
12699
96Su Doku
15217
97Large non-Mersenne prime
40231
98Anagramic squares
10022
99Largest exponential
27853
100Arranged probability
14495