Cache update: 60 minutes

Problems Archives

The problems archives table shows problems 1 to 699. 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
933843
2Even Fibonacci numbers
743534
3Largest prime factor
531628
4Largest palindrome product
469692
5Smallest multiple
474225
6Sum square difference
477255
710001st prime
407505
8Largest product in a series
340279
9Special Pythagorean triplet
345670
10Summation of primes
316124
11Largest product in a grid
225921
12Highly divisible triangular number
212618
13Large sum
218068
14Longest Collatz sequence
218339
15Lattice paths
179734
16Power digit sum
220596
17Number letter counts
145252
18Maximum path sum I
139063
19Counting Sundays
129320
20Factorial digit sum
191049
21Amicable numbers
140299
22Names scores
128683
23Non-abundant sums
99313
24Lexicographic permutations
109747
251000-digit Fibonacci number
149385
26Reciprocal cycles
79883
27Quadratic primes
83182
28Number spiral diagonals
103754
29Distinct powers
100694
30Digit fifth powers
105299
31Coin sums
80961
32Pandigital products
67610
33Digit cancelling fractions
68133
34Digit factorials
90060
35Circular primes
80798
36Double-base palindromes
84892
37Truncatable primes
69976
38Pandigital multiples
59732
39Integer right triangles
69539
40Champernowne's constant
76335
41Pandigital prime
64610
42Coded triangle numbers
70852
43Sub-string divisibility
56569
44Pentagon numbers
55265
45Triangular, pentagonal, and hexagonal
67635
46Goldbach's other conjecture
58271
47Distinct primes factors
54858
48Self powers
107944
49Prime permutations
54779
50Consecutive prime sum
59239