Cache update: 45 minutes

## Problems Archives

• Problem 699 will be accessible in 4 hours, 37 minutes (Sunday, 26th January 2020, 10:00 am)

The problems archives table shows problems 1 to 688. 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
30982
52Permuted multiples
61043
53Combinatoric selections
55085
54Poker hands
33176
55Lychrel numbers
50152
56Powerful digit sum
54434
57Square root convergents
38419
58Spiral primes
37153
59XOR decryption
38416
60Prime pair sets
24263
61Cyclical figurate numbers
23284
62Cubic permutations
28808
63Powerful digit counts
40041
64Odd period square roots
20169
65Convergents of e
27561
66Diophantine equation
17889
67Maximum path sum II
90499
68Magic 5-gon ring
18900
69Totient maximum
31924
70Totient permutation
20309
71Ordered fractions
26940
72Counting fractions
20399
73Counting fractions in a range
23085
74Digit factorial chains
24577
75Singular integer right triangles
16305
76Counting summations
26383
77Prime summations
17391
78Coin partitions
15252
79Passcode derivation
38587
80Square root digital expansion
18125
81Path sum: two ways
31912
82Path sum: three ways
19373
83Path sum: four ways
16544
84Monopoly odds
11391
85Counting rectangles
22756
86Cuboid route
11447
87Prime power triples
19120
88Product-sum numbers
8963
89Roman numerals
19612
90Cube digit pairs
10074
91Right triangles with integer coordinates
14033
92Square digit chains
38798
93Arithmetic expressions
10559
94Almost equilateral triangles
11023
95Amicable chains
12876
96Su Doku
15441
97Large non-Mersenne prime
40730
98Anagramic squares
10173
99Largest exponential
28243
100Arranged probability
14716