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Problems Archives

The problems archives table shows problems 1 to 652. 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
28871
52Permuted multiples
57489
53Combinatoric selections
51840
54Poker hands
30914
55Lychrel numbers
47202
56Powerful digit sum
51189
57Square root convergents
36011
58Spiral primes
34864
59XOR decryption
36309
60Prime pair sets
22594
61Cyclical figurate numbers
21840
62Cubic permutations
26960
63Powerful digit counts
37617
64Odd period square roots
18941
65Convergents of e
25991
66Diophantine equation
16813
67Maximum path sum II
85623
68Magic 5-gon ring
17768
69Totient maximum
29788
70Totient permutation
19147
71Ordered fractions
25242
72Counting fractions
19186
73Counting fractions in a range
21753
74Digit factorial chains
23104
75Singular integer right triangles
15312
76Counting summations
24765
77Prime summations
16311
78Coin partitions
14351
79Passcode derivation
36813
80Square root digital expansion
17112
81Path sum: two ways
30169
82Path sum: three ways
18287
83Path sum: four ways
15632
84Monopoly odds
10671
85Counting rectangles
21440
86Cuboid route
10770
87Prime power triples
17979
88Product-sum numbers
8387
89Roman numerals
18621
90Cube digit pairs
9434
91Right triangles with integer coordinates
13214
92Square digit chains
36712
93Arithmetic expressions
9902
94Almost equilateral triangles
10360
95Amicable chains
12088
96Su Doku
14524
97Large non-Mersenne prime
38737
98Anagramic squares
9553
99Largest exponential
26593
100Arranged probability
13756