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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
730854
2Even Fibonacci numbers
588227
3Largest prime factor
421516
4Largest palindrome product
375644
5Smallest multiple
384405
6Sum square difference
386653
710001st prime
330970
8Largest product in a series
280081
9Special Pythagorean triplet
282670
10Summation of primes
259377
11Largest product in a grid
188412
12Highly divisible triangular number
175814
13Large sum
181556
14Longest Collatz sequence
180950
15Lattice paths
149641
16Power digit sum
183194
17Number letter counts
121973
18Maximum path sum I
117210
19Counting Sundays
108939
20Factorial digit sum
160885
21Amicable numbers
117419
22Names scores
108544
23Non-abundant sums
83379
24Lexicographic permutations
92749
251000-digit Fibonacci number
125503
26Reciprocal cycles
67314
27Quadratic primes
70422
28Number spiral diagonals
88743
29Distinct powers
84565
30Digit fifth powers
88614
31Coin sums
67695
32Pandigital products
57185
33Digit cancelling fractions
57857
34Digit factorials
76202
35Circular primes
68800
36Double-base palindromes
72429
37Truncatable primes
59420
38Pandigital multiples
50647
39Integer right triangles
58840
40Champernowne's constant
64945
41Pandigital prime
54803
42Coded triangle numbers
60666
43Sub-string divisibility
47743
44Pentagon numbers
46386
45Triangular, pentagonal, and hexagonal
57676
46Goldbach's other conjecture
49073
47Distinct primes factors
46402
48Self powers
92540
49Prime permutations
46393
50Consecutive prime sum
49962