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Problems Archives

The problems archives table shows problems 1 to 699. 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
31519
52Permuted multiples
61932
53Combinatoric selections
55888
54Poker hands
33763
55Lychrel numbers
50913
56Powerful digit sum
55219
57Square root convergents
39019
58Spiral primes
37699
59XOR decryption
38915
60Prime pair sets
24675
61Cyclical figurate numbers
23617
62Cubic permutations
29231
63Powerful digit counts
40637
64Odd period square roots
20467
65Convergents of e
27952
66Diophantine equation
18161
67Maximum path sum II
91701
68Magic 5-gon ring
19185
69Totient maximum
32445
70Totient permutation
20612
71Ordered fractions
27324
72Counting fractions
20696
73Counting fractions in a range
23377
74Digit factorial chains
24933
75Singular integer right triangles
16563
76Counting summations
26747
77Prime summations
17669
78Coin partitions
15495
79Passcode derivation
39003
80Square root digital expansion
18397
81Path sum: two ways
32352
82Path sum: three ways
19654
83Path sum: four ways
16813
84Monopoly odds
11571
85Counting rectangles
23044
86Cuboid route
11618
87Prime power triples
19409
88Product-sum numbers
9115
89Roman numerals
19853
90Cube digit pairs
10234
91Right triangles with integer coordinates
14239
92Square digit chains
39273
93Arithmetic expressions
10729
94Almost equilateral triangles
11205
95Amicable chains
13079
96Su Doku
15701
97Large non-Mersenne prime
41125
98Anagramic squares
10316
99Largest exponential
28622
100Arranged probability
14923