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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
475277
2Even Fibonacci numbers
389957
3Largest prime factor
283364
4Largest palindrome product
256028
5Smallest multiple
268316
6Sum square difference
270223
710001st prime
231641
8Largest product in a series
201114
9Special Pythagorean triplet
200605
10Summation of primes
184165
11Largest product in a grid
136619
12Highly divisible triangular number
125084
13Large sum
131536
14Longest Collatz sequence
129646
15Lattice paths
108027
16Power digit sum
133995
17Number letter counts
88774
18Maximum path sum I
86416
19Counting Sundays
79844
20Factorial digit sum
120447
21Amicable numbers
85779
22Names scores
79886
23Non-abundant sums
60583
24Lexicographic permutations
68684
251000-digit Fibonacci number
92978
26Reciprocal cycles
49378
27Quadratic primes
51913
28Number spiral diagonals
67333
29Distinct powers
62226
30Digit fifth powers
65789
31Coin sums
49370
32Pandigital products
42180
33Digit cancelling fractions
43213
34Digit factorials
57082
35Circular primes
52001
36Double-base palindromes
55039
37Truncatable primes
44384
38Pandigital multiples
37751
39Integer right triangles
43725
40Champernowne's constant
48619
41Pandigital prime
40822
42Coded triangle numbers
46157
43Sub-string divisibility
35127
44Pentagon numbers
33893
45Triangular, pentagonal, and hexagonal
43807
46Goldbach's other conjecture
36054
47Distinct primes factors
34348
48Self powers
71927
49Prime permutations
34222
50Consecutive prime sum
36714