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Problems Archives

The problems archives table shows problems 1 to 610. 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
731098
2Even Fibonacci numbers
588390
3Largest prime factor
421621
4Largest palindrome product
375752
5Smallest multiple
384501
6Sum square difference
386752
710001st prime
331070
8Largest product in a series
280146
9Special Pythagorean triplet
282734
10Summation of primes
259437
11Largest product in a grid
188445
12Highly divisible triangular number
175861
13Large sum
181611
14Longest Collatz sequence
180995
15Lattice paths
149677
16Power digit sum
183235
17Number letter counts
122004
18Maximum path sum I
117238
19Counting Sundays
108961
20Factorial digit sum
160916
21Amicable numbers
117441
22Names scores
108568
23Non-abundant sums
83399
24Lexicographic permutations
92771
251000-digit Fibonacci number
125527
26Reciprocal cycles
67329
27Quadratic primes
70439
28Number spiral diagonals
88759
29Distinct powers
84588
30Digit fifth powers
88638
31Coin sums
67714
32Pandigital products
57195
33Digit cancelling fractions
57866
34Digit factorials
76217
35Circular primes
68812
36Double-base palindromes
72440
37Truncatable primes
59435
38Pandigital multiples
50655
39Integer right triangles
58855
40Champernowne's constant
64954
41Pandigital prime
54811
42Coded triangle numbers
60680
43Sub-string divisibility
47755
44Pentagon numbers
46393
45Triangular, pentagonal, and hexagonal
57678
46Goldbach's other conjecture
49079
47Distinct primes factors
46408
48Self powers
92556
49Prime permutations
46400
50Consecutive prime sum
49977