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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
482186
2Even Fibonacci numbers
395481
3Largest prime factor
287273
4Largest palindrome product
259491
5Smallest multiple
271580
6Sum square difference
273527
710001st prime
234473
8Largest product in a series
203394
9Special Pythagorean triplet
202968
10Summation of primes
186367
11Largest product in a grid
138147
12Highly divisible triangular number
126580
13Large sum
133007
14Longest Collatz sequence
131144
15Lattice paths
109242
16Power digit sum
135384
17Number letter counts
89751
18Maximum path sum I
87302
19Counting Sundays
80671
20Factorial digit sum
121629
21Amicable numbers
86737
22Names scores
80726
23Non-abundant sums
61257
24Lexicographic permutations
69429
251000-digit Fibonacci number
93929
26Reciprocal cycles
49910
27Quadratic primes
52463
28Number spiral diagonals
67970
29Distinct powers
62886
30Digit fifth powers
66461
31Coin sums
49917
32Pandigital products
42638
33Digit cancelling fractions
43672
34Digit factorials
57640
35Circular primes
52513
36Double-base palindromes
55562
37Truncatable primes
44842
38Pandigital multiples
38145
39Integer right triangles
44157
40Champernowne's constant
49081
41Pandigital prime
41213
42Coded triangle numbers
46563
43Sub-string divisibility
35504
44Pentagon numbers
34264
45Triangular, pentagonal, and hexagonal
44224
46Goldbach's other conjecture
36442
47Distinct primes factors
34714
48Self powers
72516
49Prime permutations
34600
50Consecutive prime sum
37111