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Problems Archives

The problems archives table shows problems 1 to 512. 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
1Multiples of 3 and 5
489923
2Even Fibonacci numbers
401519
3Largest prime factor
291467
4Largest palindrome product
263142
5Smallest multiple
275184
6Sum square difference
277050
710001st prime
237506
8Largest product in a series
205839
9Special Pythagorean triplet
205480
10Summation of primes
188667
11Largest product in a grid
139805
12Highly divisible triangular number
128154
13Large sum
134578
14Longest Collatz sequence
132723
15Lattice paths
110535
16Power digit sum
136886
17Number letter counts
90857
18Maximum path sum I
88352
19Counting Sundays
81626
20Factorial digit sum
122933
21Amicable numbers
87770
22Names scores
81699
23Non-abundant sums
62012
24Lexicographic permutations
70265
251000-digit Fibonacci number
94975
26Reciprocal cycles
50505
27Quadratic primes
53113
28Number spiral diagonals
68672
29Distinct powers
63623
30Digit fifth powers
67229
31Coin sums
50555
32Pandigital products
43178
33Digit cancelling fractions
44183
34Digit factorials
58301
35Circular primes
53111
36Double-base palindromes
56194
37Truncatable primes
45368
38Pandigital multiples
38604
39Integer right triangles
44694
40Champernowne's constant
49644
41Pandigital prime
41698
42Coded triangle numbers
47049
43Sub-string divisibility
35930
44Pentagon numbers
34669
45Triangular, pentagonal, and hexagonal
44677
46Goldbach's other conjecture
36876
47Distinct primes factors
35120
48Self powers
73170
49Prime permutations
34989
50Consecutive prime sum
37528