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Problems Archives

The problems archives table shows problems 1 to 499. 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
449032
2Even Fibonacci numbers
368984
3Largest prime factor
268432
4Largest palindrome product
242893
5Smallest multiple
255664
6Sum square difference
257485
710001st prime
220698
8Largest product in a series
192388
9Special Pythagorean triplet
191530
10Summation of primes
175808
11Largest product in a grid
130763
12Highly divisible triangular number
119397
13Large sum
125932
14Longest Collatz sequence
123911
15Lattice paths
103296
16Power digit sum
128531
17Number letter counts
84991
18Maximum path sum I
82758
19Counting Sundays
76559
20Factorial digit sum
115939
21Amicable numbers
82237
22Names scores
76665
23Non-abundant sums
57969
24Lexicographic permutations
66017
251000-digit Fibonacci number
89454
26Reciprocal cycles
47260
27Quadratic primes
49750
28Number spiral diagonals
64963
29Distinct powers
59739
30Digit fifth powers
63234
31Coin sums
47261
32Pandigital products
40427
33Digit cancelling fractions
41497
34Digit factorials
54953
35Circular primes
50084
36Double-base palindromes
53059
37Truncatable primes
42593
38Pandigital multiples
36222
39Integer right triangles
42011
40Champernowne's constant
46799
41Pandigital prime
39198
42Coded triangle numbers
44502
43Sub-string divisibility
33666
44Pentagon numbers
32425
45Triangular, pentagonal, and hexagonal
42216
46Goldbach's other conjecture
34581
47Distinct primes factors
32937
48Self powers
69664
49Prime permutations
32800
50Consecutive prime sum
35161