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Problems Archives

The problems archives table shows problems 1 to 536. 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
536197
2Even Fibonacci numbers
437560
3Largest prime factor
316664
4Largest palindrome product
284921
5Smallest multiple
296619
6Sum square difference
298360
710001st prime
255659
8Largest product in a series
220077
9Special Pythagorean triplet
220391
10Summation of primes
202441
11Largest product in a grid
149216
12Highly divisible triangular number
137422
13Large sum
143669
14Longest Collatz sequence
142028
15Lattice paths
118099
16Power digit sum
145755
17Number letter counts
96910
18Maximum path sum I
93964
19Counting Sundays
87006
20Factorial digit sum
130301
21Amicable numbers
93576
22Names scores
86818
23Non-abundant sums
66113
24Lexicographic permutations
74640
251000-digit Fibonacci number
100902
26Reciprocal cycles
53709
27Quadratic primes
56379
28Number spiral diagonals
72538
29Distinct powers
67590
30Digit fifth powers
71289
31Coin sums
53786
32Pandigital products
45850
33Digit cancelling fractions
46784
34Digit factorials
61748
35Circular primes
56088
36Double-base palindromes
59324
37Truncatable primes
48090
38Pandigital multiples
40921
39Integer right triangles
47417
40Champernowne's constant
52589
41Pandigital prime
44230
42Coded triangle numbers
49625
43Sub-string divisibility
38173
44Pentagon numbers
36901
45Triangular, pentagonal, and hexagonal
47124
46Goldbach's other conjecture
39178
47Distinct primes factors
37268
48Self powers
76824
49Prime permutations
37171
50Consecutive prime sum
39873