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Problems Archives

The problems archives table shows problems 1 to 504. 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
457971
2Even Fibonacci numbers
376106
3Largest prime factor
273468
4Largest palindrome product
247316
5Smallest multiple
259900
6Sum square difference
261703
710001st prime
224380
8Largest product in a series
195344
9Special Pythagorean triplet
194573
10Summation of primes
178659
11Largest product in a grid
132762
12Highly divisible triangular number
121313
13Large sum
127862
14Longest Collatz sequence
125846
15Lattice paths
104927
16Power digit sum
130370
17Number letter counts
86286
18Maximum path sum I
84020
19Counting Sundays
77711
20Factorial digit sum
117483
21Amicable numbers
83479
22Names scores
77820
23Non-abundant sums
58894
24Lexicographic permutations
66926
251000-digit Fibonacci number
90704
26Reciprocal cycles
48016
27Quadratic primes
50516
28Number spiral diagonals
65814
29Distinct powers
60600
30Digit fifth powers
64098
31Coin sums
48004
32Pandigital products
41034
33Digit cancelling fractions
42079
34Digit factorials
55698
35Circular primes
50740
36Double-base palindromes
53731
37Truncatable primes
43197
38Pandigital multiples
36710
39Integer right triangles
42581
40Champernowne's constant
47426
41Pandigital prime
39738
42Coded triangle numbers
45062
43Sub-string divisibility
34151
44Pentagon numbers
32932
45Triangular, pentagonal, and hexagonal
42746
46Goldbach's other conjecture
35079
47Distinct primes factors
33392
48Self powers
70441
49Prime permutations
33257
50Consecutive prime sum
35690