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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
475344
2Even Fibonacci numbers
390006
3Largest prime factor
283404
4Largest palindrome product
256054
5Smallest multiple
268343
6Sum square difference
270247
710001st prime
231665
8Largest product in a series
201128
9Special Pythagorean triplet
200629
10Summation of primes
184189
11Largest product in a grid
136629
12Highly divisible triangular number
125102
13Large sum
131544
14Longest Collatz sequence
129658
15Lattice paths
108038
16Power digit sum
134014
17Number letter counts
88787
18Maximum path sum I
86428
19Counting Sundays
79856
20Factorial digit sum
120459
21Amicable numbers
85786
22Names scores
79890
23Non-abundant sums
60592
24Lexicographic permutations
68693
251000-digit Fibonacci number
92991
26Reciprocal cycles
49386
27Quadratic primes
51919
28Number spiral diagonals
67341
29Distinct powers
62231
30Digit fifth powers
65795
31Coin sums
49377
32Pandigital products
42185
33Digit cancelling fractions
43215
34Digit factorials
57089
35Circular primes
52009
36Double-base palindromes
55048
37Truncatable primes
44394
38Pandigital multiples
37758
39Integer right triangles
43730
40Champernowne's constant
48626
41Pandigital prime
40828
42Coded triangle numbers
46161
43Sub-string divisibility
35130
44Pentagon numbers
33898
45Triangular, pentagonal, and hexagonal
43808
46Goldbach's other conjecture
36056
47Distinct primes factors
34350
48Self powers
71933
49Prime permutations
34226
50Consecutive prime sum
36716