Search ProblemsRSS Feed
Cache update: 60 minutes

Problems Archives

The problems archives table shows problems 1 to 624. 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
773602
2Even Fibonacci numbers
620914
3Largest prime factor
444414
4Largest palindrome product
395304
5Smallest multiple
403245
6Sum square difference
405664
710001st prime
347153
8Largest product in a series
292829
9Special Pythagorean triplet
295977
10Summation of primes
271430
11Largest product in a grid
196481
12Highly divisible triangular number
183806
13Large sum
189405
14Longest Collatz sequence
189058
15Lattice paths
156218
16Power digit sum
191114
17Number letter counts
127047
18Maximum path sum I
122061
19Counting Sundays
113455
20Factorial digit sum
167290
21Amicable numbers
122549
22Names scores
113062
23Non-abundant sums
86975
24Lexicographic permutations
96602
251000-digit Fibonacci number
130686
26Reciprocal cycles
70078
27Quadratic primes
73246
28Number spiral diagonals
91973
29Distinct powers
88068
30Digit fifth powers
92267
31Coin sums
70633
32Pandigital products
59504
33Digit cancelling fractions
60214
34Digit factorials
79213
35Circular primes
71469
36Double-base palindromes
75289
37Truncatable primes
61859
38Pandigital multiples
52687
39Integer right triangles
61313
40Champernowne's constant
67500
41Pandigital prime
57075
42Coded triangle numbers
62982
43Sub-string divisibility
49808
44Pentagon numbers
48394
45Triangular, pentagonal, and hexagonal
59969
46Goldbach's other conjecture
51200
47Distinct primes factors
48343
48Self powers
95976
49Prime permutations
48341
50Consecutive prime sum
52041