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## Problems Archives

The problems archives table shows problems 1 to 751. 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.

ID

Description / TitleSolved By
51Prime digit replacements
33886
52Permuted multiples
65445
53Combinatoric selections
59140
54Poker hands
36139
55Lychrel numbers
53982
56Powerful digit sum
58376
57Square root convergents
41686
58Spiral primes
40266
59XOR decryption
41293
60Prime pair sets
26644
61Cyclical figurate numbers
25409
62Cubic permutations
31405
63Powerful digit counts
43230
64Odd period square roots
22065
65Convergents of e
29804
66Diophantine equation
19552
67Maximum path sum II
96241
68Magic 5-gon ring
20651
69Totient maximum
34743
70Totient permutation
22163
71Ordered fractions
29200
72Counting fractions
22238
73Counting fractions in a range
24943
74Digit factorial chains
26626
75Singular integer right triangles
17870
76Counting summations
28497
77Prime summations
19026
78Coin partitions
16722
79Passcode derivation
40964
80Square root digital expansion
19700
81Path sum: two ways
34209
82Path sum: three ways
20943
83Path sum: four ways
17980
84Monopoly odds
12461
85Counting rectangles
24561
86Cuboid route
12553
87Prime power triples
20748
88Product-sum numbers
9928
89Roman numerals
21047
90Cube digit pairs
11102
91Right triangles with integer coordinates
15275
92Square digit chains
41515
93Arithmetic expressions
11604
94Almost equilateral triangles
12148
95Amicable chains
14091
96Su Doku
16960
97Large non-Mersenne prime
43123
98Anagramic squares
11184
99Largest exponential
30417
100Arranged probability
16074