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Problems Archives

The problems archives table shows problems 1 to 670. 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
30147
52Permuted multiples
59544
53Combinatoric selections
53749
54Poker hands
32283
55Lychrel numbers
48951
56Powerful digit sum
53079
57Square root convergents
37407
58Spiral primes
36229
59XOR decryption
37590
60Prime pair sets
23604
61Cyclical figurate numbers
22710
62Cubic permutations
28061
63Powerful digit counts
39021
64Odd period square roots
19691
65Convergents of e
26945
66Diophantine equation
17488
67Maximum path sum II
88491
68Magic 5-gon ring
18460
69Totient maximum
31078
70Totient permutation
19867
71Ordered fractions
26262
72Counting fractions
19944
73Counting fractions in a range
22561
74Digit factorial chains
23985
75Singular integer right triangles
15941
76Counting summations
25756
77Prime summations
16980
78Coin partitions
14898
79Passcode derivation
37858
80Square root digital expansion
17730
81Path sum: two ways
31151
82Path sum: three ways
18933
83Path sum: four ways
16184
84Monopoly odds
11119
85Counting rectangles
22225
86Cuboid route
11161
87Prime power triples
18660
88Product-sum numbers
8709
89Roman numerals
19193
90Cube digit pairs
9816
91Right triangles with integer coordinates
13714
92Square digit chains
37924
93Arithmetic expressions
10279
94Almost equilateral triangles
10769
95Amicable chains
12562
96Su Doku
15047
97Large non-Mersenne prime
39889
98Anagramic squares
9914
99Largest exponential
27566
100Arranged probability
14321