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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
475377
2Even Fibonacci numbers
390035
3Largest prime factor
283420
4Largest palindrome product
256067
5Smallest multiple
268360
6Sum square difference
270263
710001st prime
231677
8Largest product in a series
201136
9Special Pythagorean triplet
200643
10Summation of primes
184197
11Largest product in a grid
136635
12Highly divisible triangular number
125105
13Large sum
131552
14Longest Collatz sequence
129662
15Lattice paths
108041
16Power digit sum
134018
17Number letter counts
88791
18Maximum path sum I
86430
19Counting Sundays
79861
20Factorial digit sum
120461
21Amicable numbers
85789
22Names scores
79895
23Non-abundant sums
60595
24Lexicographic permutations
68696
251000-digit Fibonacci number
92992
26Reciprocal cycles
49391
27Quadratic primes
51921
28Number spiral diagonals
67342
29Distinct powers
62234
30Digit fifth powers
65797
31Coin sums
49380
32Pandigital products
42189
33Digit cancelling fractions
43218
34Digit factorials
57092
35Circular primes
52010
36Double-base palindromes
55050
37Truncatable primes
44397
38Pandigital multiples
37761
39Integer right triangles
43732
40Champernowne's constant
48629
41Pandigital prime
40835
42Coded triangle numbers
46164
43Sub-string divisibility
35133
44Pentagon numbers
33898
45Triangular, pentagonal, and hexagonal
43810
46Goldbach's other conjecture
36059
47Distinct primes factors
34354
48Self powers
71937
49Prime permutations
34226
50Consecutive prime sum
36718