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Problems Archives

The problems archives table shows problems 1 to 535. 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
535432
2Even Fibonacci numbers
436951
3Largest prime factor
316260
4Largest palindrome product
284555
5Smallest multiple
296233
6Sum square difference
297993
710001st prime
255347
8Largest product in a series
219830
9Special Pythagorean triplet
220128
10Summation of primes
202197
11Largest product in a grid
149044
12Highly divisible triangular number
137267
13Large sum
143505
14Longest Collatz sequence
141860
15Lattice paths
117951
16Power digit sum
145591
17Number letter counts
96788
18Maximum path sum I
93865
19Counting Sundays
86920
20Factorial digit sum
130183
21Amicable numbers
93482
22Names scores
86726
23Non-abundant sums
66037
24Lexicographic permutations
74577
251000-digit Fibonacci number
100802
26Reciprocal cycles
53656
27Quadratic primes
56325
28Number spiral diagonals
72465
29Distinct powers
67515
30Digit fifth powers
71217
31Coin sums
53726
32Pandigital products
45794
33Digit cancelling fractions
46725
34Digit factorials
61674
35Circular primes
56037
36Double-base palindromes
59258
37Truncatable primes
48045
38Pandigital multiples
40876
39Integer right triangles
47364
40Champernowne's constant
52533
41Pandigital prime
44179
42Coded triangle numbers
49578
43Sub-string divisibility
38130
44Pentagon numbers
36855
45Triangular, pentagonal, and hexagonal
47073
46Goldbach's other conjecture
39139
47Distinct primes factors
37229
48Self powers
76754
49Prime permutations
37133
50Consecutive prime sum
39822