RSS Feedsecure_iconYou are currently using a secure connection

Problems Archives

The problems archives table shows problems 1 to 507. 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
464388
2Even Fibonacci numbers
381170
3Largest prime factor
277121
4Largest palindrome product
250511
5Smallest multiple
263044
6Sum square difference
264863
710001st prime
227042
8Largest product in a series
197447
9Special Pythagorean triplet
196791
10Summation of primes
180685
11Largest product in a grid
134172
12Highly divisible triangular number
122703
13Large sum
129225
14Longest Collatz sequence
127289
15Lattice paths
106120
16Power digit sum
131742
17Number letter counts
87225
18Maximum path sum I
84924
19Counting Sundays
78503
20Factorial digit sum
118592
21Amicable numbers
84357
22Names scores
78617
23Non-abundant sums
59528
24Lexicographic permutations
67605
251000-digit Fibonacci number
91551
26Reciprocal cycles
48549
27Quadratic primes
51028
28Number spiral diagonals
66395
29Distinct powers
61216
30Digit fifth powers
64737
31Coin sums
48497
32Pandigital products
41451
33Digit cancelling fractions
42503
34Digit factorials
56195
35Circular primes
51191
36Double-base palindromes
54198
37Truncatable primes
43638
38Pandigital multiples
37075
39Integer right triangles
42991
40Champernowne's constant
47837
41Pandigital prime
40134
42Coded triangle numbers
45455
43Sub-string divisibility
34495
44Pentagon numbers
33280
45Triangular, pentagonal, and hexagonal
43124
46Goldbach's other conjecture
35416
47Distinct primes factors
33757
48Self powers
71016
49Prime permutations
33609
50Consecutive prime sum
36072