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Problems Archives

The problems archives table shows problems 1 to 548. 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
559069
2Even Fibonacci numbers
455442
3Largest prime factor
329195
4Largest palindrome product
295831
5Smallest multiple
307201
6Sum square difference
308950
710001st prime
264866
8Largest product in a series
227342
9Special Pythagorean triplet
227806
10Summation of primes
209371
11Largest product in a grid
153931
12Highly divisible triangular number
141991
13Large sum
148179
14Longest Collatz sequence
146611
15Lattice paths
121836
16Power digit sum
150158
17Number letter counts
99914
18Maximum path sum I
96815
19Counting Sundays
89609
20Factorial digit sum
133899
21Amicable numbers
96381
22Names scores
89346
23Non-abundant sums
68149
24Lexicographic permutations
76757
251000-digit Fibonacci number
103788
26Reciprocal cycles
55335
27Quadratic primes
58031
28Number spiral diagonals
74357
29Distinct powers
69533
30Digit fifth powers
73282
31Coin sums
55401
32Pandigital products
47156
33Digit cancelling fractions
48025
34Digit factorials
63364
35Circular primes
57521
36Double-base palindromes
60763
37Truncatable primes
49349
38Pandigital multiples
41981
39Integer right triangles
48695
40Champernowne's constant
53970
41Pandigital prime
45394
42Coded triangle numbers
50867
43Sub-string divisibility
39222
44Pentagon numbers
37999
45Triangular, pentagonal, and hexagonal
48301
46Goldbach's other conjecture
40293
47Distinct primes factors
38289
48Self powers
78620
49Prime permutations
38220
50Consecutive prime sum
41013