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Problems Archives

The problems archives table shows problems 1 to 617. 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
26774
52Permuted multiples
54048
53Combinatoric selections
48716
54Poker hands
28764
55Lychrel numbers
44312
56Powerful digit sum
48052
57Square root convergents
33736
58Spiral primes
32669
59XOR decryption
34219
60Prime pair sets
20984
61Cyclical figurate numbers
20414
62Cubic permutations
25188
63Powerful digit counts
35262
64Odd period square roots
17748
65Convergents of e
24420
66Diophantine equation
15772
67Maximum path sum II
80706
68Magic 5-gon ring
16684
69Totient maximum
27810
70Totient permutation
18003
71Ordered fractions
23563
72Counting fractions
18002
73Counting fractions in a range
20483
74Digit factorial chains
21634
75Singular integer right triangles
14377
76Counting summations
23231
77Prime summations
15318
78Coin partitions
13463
79Passcode derivation
35034
80Square root digital expansion
16107
81Path sum: two ways
28350
82Path sum: three ways
17202
83Path sum: four ways
14719
84Monopoly odds
10052
85Counting rectangles
20167
86Cuboid route
10157
87Prime power triples
16890
88Product-sum numbers
7868
89Roman numerals
17687
90Cube digit pairs
8841
91Right triangles with integer coordinates
12464
92Square digit chains
34660
93Arithmetic expressions
9327
94Almost equilateral triangles
9738
95Amicable chains
11364
96Su Doku
13675
97Large non-Mersenne prime
36890
98Anagramic squares
8998
99Largest exponential
25065
100Arranged probability
12981