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Problems Archives

The problems archives table shows problems 1 to 641. 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
28373
52Permuted multiples
56721
53Combinatoric selections
51148
54Poker hands
30382
55Lychrel numbers
46520
56Powerful digit sum
50446
57Square root convergents
35459
58Spiral primes
34341
59XOR decryption
35827
60Prime pair sets
22209
61Cyclical figurate numbers
21469
62Cubic permutations
26516
63Powerful digit counts
37049
64Odd period square roots
18635
65Convergents of e
25582
66Diophantine equation
16546
67Maximum path sum II
84453
68Magic 5-gon ring
17517
69Totient maximum
29307
70Totient permutation
18875
71Ordered fractions
24820
72Counting fractions
18897
73Counting fractions in a range
21431
74Digit factorial chains
22720
75Singular integer right triangles
15090
76Counting summations
24381
77Prime summations
16066
78Coin partitions
14147
79Passcode derivation
36411
80Square root digital expansion
16882
81Path sum: two ways
29716
82Path sum: three ways
18028
83Path sum: four ways
15419
84Monopoly odds
10539
85Counting rectangles
21125
86Cuboid route
10630
87Prime power triples
17715
88Product-sum numbers
8248
89Roman numerals
18387
90Cube digit pairs
9270
91Right triangles with integer coordinates
13006
92Square digit chains
36238
93Arithmetic expressions
9756
94Almost equilateral triangles
10183
95Amicable chains
11895
96Su Doku
14321
97Large non-Mersenne prime
38302
98Anagramic squares
9398
99Largest exponential
26228
100Arranged probability
13571