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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
449498
2Even Fibonacci numbers
369344
3Largest prime factor
268710
4Largest palindrome product
243134
5Smallest multiple
255886
6Sum square difference
257718
710001st prime
220893
8Largest product in a series
192546
9Special Pythagorean triplet
191672
10Summation of primes
175934
11Largest product in a grid
130876
12Highly divisible triangular number
119499
13Large sum
126019
14Longest Collatz sequence
123996
15Lattice paths
103372
16Power digit sum
128641
17Number letter counts
85066
18Maximum path sum I
82837
19Counting Sundays
76638
20Factorial digit sum
116035
21Amicable numbers
82332
22Names scores
76753
23Non-abundant sums
58032
24Lexicographic permutations
66080
251000-digit Fibonacci number
89548
26Reciprocal cycles
47296
27Quadratic primes
49780
28Number spiral diagonals
65010
29Distinct powers
59797
30Digit fifth powers
63280
31Coin sums
47298
32Pandigital products
40459
33Digit cancelling fractions
41524
34Digit factorials
54988
35Circular primes
50111
36Double-base palindromes
53090
37Truncatable primes
42617
38Pandigital multiples
36250
39Integer right triangles
42049
40Champernowne's constant
46834
41Pandigital prime
39224
42Coded triangle numbers
44526
43Sub-string divisibility
33694
44Pentagon numbers
32455
45Triangular, pentagonal, and hexagonal
42250
46Goldbach's other conjecture
34612
47Distinct primes factors
32962
48Self powers
69705
49Prime permutations
32822
50Consecutive prime sum
35188