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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
488607
2Even Fibonacci numbers
400492
3Largest prime factor
290741
4Largest palindrome product
262518
5Smallest multiple
274557
6Sum square difference
276439
710001st prime
236984
8Largest product in a series
205409
9Special Pythagorean triplet
205029
10Summation of primes
188265
11Largest product in a grid
139513
12Highly divisible triangular number
127881
13Large sum
134305
14Longest Collatz sequence
132452
15Lattice paths
110304
16Power digit sum
136629
17Number letter counts
90670
18Maximum path sum I
88177
19Counting Sundays
81465
20Factorial digit sum
122701
21Amicable numbers
87602
22Names scores
81538
23Non-abundant sums
61886
24Lexicographic permutations
70123
251000-digit Fibonacci number
94808
26Reciprocal cycles
50406
27Quadratic primes
53008
28Number spiral diagonals
68555
29Distinct powers
63500
30Digit fifth powers
67106
31Coin sums
50440
32Pandigital products
43080
33Digit cancelling fractions
44096
34Digit factorials
58180
35Circular primes
53006
36Double-base palindromes
56084
37Truncatable primes
45274
38Pandigital multiples
38524
39Integer right triangles
44615
40Champernowne's constant
49547
41Pandigital prime
41626
42Coded triangle numbers
46983
43Sub-string divisibility
35862
44Pentagon numbers
34608
45Triangular, pentagonal, and hexagonal
44608
46Goldbach's other conjecture
36796
47Distinct primes factors
35040
48Self powers
73069
49Prime permutations
34921
50Consecutive prime sum
37466