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Problems Archives

The problems archives table shows problems 1 to 621. 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
27149
52Permuted multiples
54716
53Combinatoric selections
49315
54Poker hands
29131
55Lychrel numbers
44849
56Powerful digit sum
48624
57Square root convergents
34163
58Spiral primes
33065
59XOR decryption
34599
60Prime pair sets
21277
61Cyclical figurate numbers
20678
62Cubic permutations
25515
63Powerful digit counts
35705
64Odd period square roots
17956
65Convergents of e
24689
66Diophantine equation
15964
67Maximum path sum II
81572
68Magic 5-gon ring
16895
69Totient maximum
28163
70Totient permutation
18239
71Ordered fractions
23849
72Counting fractions
18224
73Counting fractions in a range
20717
74Digit factorial chains
21895
75Singular integer right triangles
14568
76Counting summations
23505
77Prime summations
15509
78Coin partitions
13646
79Passcode derivation
35354
80Square root digital expansion
16298
81Path sum: two ways
28696
82Path sum: three ways
17418
83Path sum: four ways
14901
84Monopoly odds
10152
85Counting rectangles
20388
86Cuboid route
10267
87Prime power triples
17085
88Product-sum numbers
7962
89Roman numerals
17834
90Cube digit pairs
8947
91Right triangles with integer coordinates
12590
92Square digit chains
35028
93Arithmetic expressions
9416
94Almost equilateral triangles
9840
95Amicable chains
11468
96Su Doku
13810
97Large non-Mersenne prime
37233
98Anagramic squares
9075
99Largest exponential
25307
100Arranged probability
13095