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Problems Archives

The problems archives table shows problems 1 to 536. 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
537419
2Even Fibonacci numbers
438507
3Largest prime factor
317306
4Largest palindrome product
285498
5Smallest multiple
297175
6Sum square difference
298888
710001st prime
256094
8Largest product in a series
220419
9Special Pythagorean triplet
220752
10Summation of primes
202766
11Largest product in a grid
149462
12Highly divisible triangular number
137648
13Large sum
143896
14Longest Collatz sequence
142284
15Lattice paths
118285
16Power digit sum
145959
17Number letter counts
97044
18Maximum path sum I
94094
19Counting Sundays
87135
20Factorial digit sum
130465
21Amicable numbers
93711
22Names scores
86952
23Non-abundant sums
66195
24Lexicographic permutations
74746
251000-digit Fibonacci number
101033
26Reciprocal cycles
53798
27Quadratic primes
56471
28Number spiral diagonals
72627
29Distinct powers
67695
30Digit fifth powers
71372
31Coin sums
53875
32Pandigital products
45925
33Digit cancelling fractions
46841
34Digit factorials
61832
35Circular primes
56164
36Double-base palindromes
59402
37Truncatable primes
48161
38Pandigital multiples
40979
39Integer right triangles
47486
40Champernowne's constant
52664
41Pandigital prime
44290
42Coded triangle numbers
49681
43Sub-string divisibility
38237
44Pentagon numbers
36964
45Triangular, pentagonal, and hexagonal
47194
46Goldbach's other conjecture
39235
47Distinct primes factors
37313
48Self powers
76917
49Prime permutations
37236
50Consecutive prime sum
39931