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Problems Archives

The problems archives table shows problems 1 to 512. 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
481512
2Even Fibonacci numbers
394932
3Largest prime factor
286877
4Largest palindrome product
259122
5Smallest multiple
271250
6Sum square difference
273187
710001st prime
234164
8Largest product in a series
203151
9Special Pythagorean triplet
202723
10Summation of primes
186134
11Largest product in a grid
137974
12Highly divisible triangular number
126403
13Large sum
132845
14Longest Collatz sequence
130976
15Lattice paths
109106
16Power digit sum
135209
17Number letter counts
89639
18Maximum path sum I
87201
19Counting Sundays
80570
20Factorial digit sum
121475
21Amicable numbers
86626
22Names scores
80633
23Non-abundant sums
61176
24Lexicographic permutations
69340
251000-digit Fibonacci number
93824
26Reciprocal cycles
49846
27Quadratic primes
52404
28Number spiral diagonals
67900
29Distinct powers
62803
30Digit fifth powers
66383
31Coin sums
49837
32Pandigital products
42585
33Digit cancelling fractions
43615
34Digit factorials
57579
35Circular primes
52459
36Double-base palindromes
55507
37Truncatable primes
44792
38Pandigital multiples
38103
39Integer right triangles
44107
40Champernowne's constant
49025
41Pandigital prime
41171
42Coded triangle numbers
46516
43Sub-string divisibility
35463
44Pentagon numbers
34219
45Triangular, pentagonal, and hexagonal
44178
46Goldbach's other conjecture
36405
47Distinct primes factors
34670
48Self powers
72448
49Prime permutations
34560
50Consecutive prime sum
37062