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
488810
2Even Fibonacci numbers
400665
3Largest prime factor
290879
4Largest palindrome product
262635
5Smallest multiple
274666
6Sum square difference
276543
710001st prime
237075
8Largest product in a series
205465
9Special Pythagorean triplet
205098
10Summation of primes
188331
11Largest product in a grid
139558
12Highly divisible triangular number
127931
13Large sum
134354
14Longest Collatz sequence
132504
15Lattice paths
110347
16Power digit sum
136669
17Number letter counts
90702
18Maximum path sum I
88204
19Counting Sundays
81491
20Factorial digit sum
122736
21Amicable numbers
87629
22Names scores
81559
23Non-abundant sums
61901
24Lexicographic permutations
70147
251000-digit Fibonacci number
94834
26Reciprocal cycles
50422
27Quadratic primes
53030
28Number spiral diagonals
68570
29Distinct powers
63519
30Digit fifth powers
67126
31Coin sums
50454
32Pandigital products
43100
33Digit cancelling fractions
44111
34Digit factorials
58198
35Circular primes
53026
36Double-base palindromes
56099
37Truncatable primes
45296
38Pandigital multiples
38537
39Integer right triangles
44629
40Champernowne's constant
49559
41Pandigital prime
41637
42Coded triangle numbers
46997
43Sub-string divisibility
35881
44Pentagon numbers
34623
45Triangular, pentagonal, and hexagonal
44621
46Goldbach's other conjecture
36814
47Distinct primes factors
35052
48Self powers
73084
49Prime permutations
34938
50Consecutive prime sum
37473