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Problems Archives

The problems archives table shows problems 1 to 502. 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
453993
2Even Fibonacci numbers
372927
3Largest prime factor
271304
4Largest palindrome product
245420
5Smallest multiple
258087
6Sum square difference
259948
710001st prime
222853
8Largest product in a series
194060
9Special Pythagorean triplet
193266
10Summation of primes
177427
11Largest product in a grid
131893
12Highly divisible triangular number
120489
13Large sum
127024
14Longest Collatz sequence
125030
15Lattice paths
104223
16Power digit sum
129568
17Number letter counts
85701
18Maximum path sum I
83491
19Counting Sundays
77225
20Factorial digit sum
116825
21Amicable numbers
82958
22Names scores
77336
23Non-abundant sums
58520
24Lexicographic permutations
66567
251000-digit Fibonacci number
90181
26Reciprocal cycles
47716
27Quadratic primes
50223
28Number spiral diagonals
65482
29Distinct powers
60249
30Digit fifth powers
63729
31Coin sums
47696
32Pandigital products
40781
33Digit cancelling fractions
41860
34Digit factorials
55398
35Circular primes
50482
36Double-base palindromes
53452
37Truncatable primes
42963
38Pandigital multiples
36528
39Integer right triangles
42348
40Champernowne's constant
47170
41Pandigital prime
39526
42Coded triangle numbers
44814
43Sub-string divisibility
33948
44Pentagon numbers
32719
45Triangular, pentagonal, and hexagonal
42517
46Goldbach's other conjecture
34882
47Distinct primes factors
33189
48Self powers
70116
49Prime permutations
33055
50Consecutive prime sum
35460