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Problems Archives

The problems archives table shows problems 1 to 610. 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
730986
2Even Fibonacci numbers
588313
3Largest prime factor
421563
4Largest palindrome product
375691
5Smallest multiple
384444
6Sum square difference
386690
710001st prime
331004
8Largest product in a series
280104
9Special Pythagorean triplet
282698
10Summation of primes
259392
11Largest product in a grid
188427
12Highly divisible triangular number
175833
13Large sum
181576
14Longest Collatz sequence
180970
15Lattice paths
149659
16Power digit sum
183207
17Number letter counts
121992
18Maximum path sum I
117224
19Counting Sundays
108947
20Factorial digit sum
160899
21Amicable numbers
117430
22Names scores
108553
23Non-abundant sums
83388
24Lexicographic permutations
92757
251000-digit Fibonacci number
125510
26Reciprocal cycles
67322
27Quadratic primes
70435
28Number spiral diagonals
88752
29Distinct powers
84576
30Digit fifth powers
88627
31Coin sums
67703
32Pandigital products
57190
33Digit cancelling fractions
57861
34Digit factorials
76206
35Circular primes
68805
36Double-base palindromes
72436
37Truncatable primes
59423
38Pandigital multiples
50653
39Integer right triangles
58845
40Champernowne's constant
64949
41Pandigital prime
54807
42Coded triangle numbers
60671
43Sub-string divisibility
47749
44Pentagon numbers
46389
45Triangular, pentagonal, and hexagonal
57677
46Goldbach's other conjecture
49078
47Distinct primes factors
46405
48Self powers
92548
49Prime permutations
46397
50Consecutive prime sum
49971