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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
482415
2Even Fibonacci numbers
395681
3Largest prime factor
287431
4Largest palindrome product
259624
5Smallest multiple
271690
6Sum square difference
273640
710001st prime
234562
8Largest product in a series
203482
9Special Pythagorean triplet
203060
10Summation of primes
186453
11Largest product in a grid
138200
12Highly divisible triangular number
126645
13Large sum
133069
14Longest Collatz sequence
131198
15Lattice paths
109285
16Power digit sum
135451
17Number letter counts
89793
18Maximum path sum I
87351
19Counting Sundays
80704
20Factorial digit sum
121672
21Amicable numbers
86777
22Names scores
80758
23Non-abundant sums
61290
24Lexicographic permutations
69459
251000-digit Fibonacci number
93971
26Reciprocal cycles
49932
27Quadratic primes
52485
28Number spiral diagonals
67992
29Distinct powers
62910
30Digit fifth powers
66487
31Coin sums
49934
32Pandigital products
42652
33Digit cancelling fractions
43694
34Digit factorials
57667
35Circular primes
52536
36Double-base palindromes
55581
37Truncatable primes
44859
38Pandigital multiples
38163
39Integer right triangles
44172
40Champernowne's constant
49095
41Pandigital prime
41231
42Coded triangle numbers
46578
43Sub-string divisibility
35522
44Pentagon numbers
34277
45Triangular, pentagonal, and hexagonal
44249
46Goldbach's other conjecture
36458
47Distinct primes factors
34735
48Self powers
72540
49Prime permutations
34618
50Consecutive prime sum
37134