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Problems Archives

The problems archives table shows problems 1 to 661. 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
29255
52Permuted multiples
58115
53Combinatoric selections
52413
54Poker hands
31345
55Lychrel numbers
47724
56Powerful digit sum
51768
57Square root convergents
36446
58Spiral primes
35293
59XOR decryption
36703
60Prime pair sets
22892
61Cyclical figurate numbers
22099
62Cubic permutations
27286
63Powerful digit counts
38054
64Odd period square roots
19159
65Convergents of e
26259
66Diophantine equation
17011
67Maximum path sum II
86526
68Magic 5-gon ring
17966
69Totient maximum
30178
70Totient permutation
19382
71Ordered fractions
25571
72Counting fractions
19430
73Counting fractions in a range
22011
74Digit factorial chains
23372
75Singular integer right triangles
15505
76Counting summations
25059
77Prime summations
16529
78Coin partitions
14522
79Passcode derivation
37164
80Square root digital expansion
17305
81Path sum: two ways
30453
82Path sum: three ways
18478
83Path sum: four ways
15800
84Monopoly odds
10802
85Counting rectangles
21695
86Cuboid route
10889
87Prime power triples
18185
88Product-sum numbers
8489
89Roman numerals
18787
90Cube digit pairs
9547
91Right triangles with integer coordinates
13365
92Square digit chains
37097
93Arithmetic expressions
10026
94Almost equilateral triangles
10487
95Amicable chains
12226
96Su Doku
14693
97Large non-Mersenne prime
39111
98Anagramic squares
9668
99Largest exponential
26906
100Arranged probability
13928