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Problems Archives

The problems archives table shows problems 1 to 627. 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
27602
52Permuted multiples
55434
53Combinatoric selections
49979
54Poker hands
29608
55Lychrel numbers
45427
56Powerful digit sum
49257
57Square root convergents
34635
58Spiral primes
33522
59XOR decryption
35067
60Prime pair sets
21597
61Cyclical figurate numbers
20970
62Cubic permutations
25893
63Powerful digit counts
36193
64Odd period square roots
18206
65Convergents of e
25019
66Diophantine equation
16184
67Maximum path sum II
82605
68Magic 5-gon ring
17115
69Totient maximum
28602
70Totient permutation
18469
71Ordered fractions
24216
72Counting fractions
18460
73Counting fractions in a range
20989
74Digit factorial chains
22209
75Singular integer right triangles
14755
76Counting summations
23844
77Prime summations
15718
78Coin partitions
13828
79Passcode derivation
35739
80Square root digital expansion
16521
81Path sum: two ways
29083
82Path sum: three ways
17651
83Path sum: four ways
15097
84Monopoly odds
10281
85Counting rectangles
20667
86Cuboid route
10406
87Prime power triples
17325
88Product-sum numbers
8071
89Roman numerals
18040
90Cube digit pairs
9070
91Right triangles with integer coordinates
12740
92Square digit chains
35478
93Arithmetic expressions
9532
94Almost equilateral triangles
9961
95Amicable chains
11621
96Su Doku
14002
97Large non-Mersenne prime
37652
98Anagramic squares
9189
99Largest exponential
25641
100Arranged probability
13257