RSS Feedsecure_iconYou are currently using a secure connection

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
481596
2Even Fibonacci numbers
395017
3Largest prime factor
286944
4Largest palindrome product
259179
5Smallest multiple
271304
6Sum square difference
273240
710001st prime
234210
8Largest product in a series
203185
9Special Pythagorean triplet
202766
10Summation of primes
186164
11Largest product in a grid
138009
12Highly divisible triangular number
126433
13Large sum
132863
14Longest Collatz sequence
131001
15Lattice paths
109123
16Power digit sum
135237
17Number letter counts
89658
18Maximum path sum I
87219
19Counting Sundays
80583
20Factorial digit sum
121495
21Amicable numbers
86648
22Names scores
80649
23Non-abundant sums
61188
24Lexicographic permutations
69353
251000-digit Fibonacci number
93845
26Reciprocal cycles
49862
27Quadratic primes
52414
28Number spiral diagonals
67910
29Distinct powers
62820
30Digit fifth powers
66392
31Coin sums
49846
32Pandigital products
42590
33Digit cancelling fractions
43624
34Digit factorials
57588
35Circular primes
52466
36Double-base palindromes
55514
37Truncatable primes
44798
38Pandigital multiples
38112
39Integer right triangles
44111
40Champernowne's constant
49029
41Pandigital prime
41175
42Coded triangle numbers
46527
43Sub-string divisibility
35468
44Pentagon numbers
34226
45Triangular, pentagonal, and hexagonal
44187
46Goldbach's other conjecture
36412
47Distinct primes factors
34679
48Self powers
72465
49Prime permutations
34563
50Consecutive prime sum
37067