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Problems Archives

The problems archives table shows problems 1 to 651. 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
834822
2Even Fibonacci numbers
667361
3Largest prime factor
476707
4Largest palindrome product
422495
5Smallest multiple
429269
6Sum square difference
431961
710001st prime
369221
8Largest product in a series
309853
9Special Pythagorean triplet
314042
10Summation of primes
287481
11Largest product in a grid
207157
12Highly divisible triangular number
194188
13Large sum
199638
14Longest Collatz sequence
199447
15Lattice paths
164667
16Power digit sum
201566
17Number letter counts
133509
18Maximum path sum I
128038
19Counting Sundays
119135
20Factorial digit sum
175634
21Amicable numbers
128759
22Names scores
118612
23Non-abundant sums
91349
24Lexicographic permutations
101309
251000-digit Fibonacci number
137387
26Reciprocal cycles
73674
27Quadratic primes
76773
28Number spiral diagonals
96258
29Distinct powers
92450
30Digit fifth powers
96829
31Coin sums
74355
32Pandigital products
62322
33Digit cancelling fractions
62976
34Digit factorials
83020
35Circular primes
74683
36Double-base palindromes
78674
37Truncatable primes
64656
38Pandigital multiples
55135
39Integer right triangles
64161
40Champernowne's constant
70563
41Pandigital prime
59764
42Coded triangle numbers
65733
43Sub-string divisibility
52186
44Pentagon numbers
50786
45Triangular, pentagonal, and hexagonal
62680
46Goldbach's other conjecture
53634
47Distinct primes factors
50569
48Self powers
100194
49Prime permutations
50611
50Consecutive prime sum
54507