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Problems Archives

The problems archives table shows problems 1 to 739. 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.


ID

Description / TitleSolved By
1Multiples of 3 and 5
966002
2Even Fibonacci numbers
769522
3Largest prime factor
552304
4Largest palindrome product
488170
5Smallest multiple
491663
6Sum square difference
494707
710001st prime
423007
8Largest product in a series
353786
9Special Pythagorean triplet
359061
10Summation of primes
328747
11Largest product in a grid
235198
12Highly divisible triangular number
221898
13Large sum
227146
14Longest Collatz sequence
227446
15Lattice paths
187427
16Power digit sum
229810
17Number letter counts
151793
18Maximum path sum I
145232
19Counting Sundays
134961
20Factorial digit sum
198801
21Amicable numbers
146587
22Names scores
134612
23Non-abundant sums
104102
24Lexicographic permutations
114706
251000-digit Fibonacci number
155678
26Reciprocal cycles
83798
27Quadratic primes
87197
28Number spiral diagonals
108092
29Distinct powers
105395
30Digit fifth powers
110009
31Coin sums
84891
32Pandigital products
71026
33Digit cancelling fractions
71439
34Digit factorials
94119
35Circular primes
84434
36Double-base palindromes
88602
37Truncatable primes
73320
38Pandigital multiples
62716
39Integer right triangles
72869
40Champernowne's constant
79833
41Pandigital prime
67790
42Coded triangle numbers
74124
43Sub-string divisibility
59498
44Pentagon numbers
58135
45Triangular, pentagonal, and hexagonal
70716
46Goldbach's other conjecture
61279
47Distinct primes factors
57615
48Self powers
112113
49Prime permutations
57543
50Consecutive prime sum
62108