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Problems Archives

The problems archives table shows problems 1 to 632. 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
798551
2Even Fibonacci numbers
639485
3Largest prime factor
457353
4Largest palindrome product
406017
5Smallest multiple
413654
6Sum square difference
416197
710001st prime
355978
8Largest product in a series
299534
9Special Pythagorean triplet
303209
10Summation of primes
277731
11Largest product in a grid
200614
12Highly divisible triangular number
187850
13Large sum
193372
14Longest Collatz sequence
193167
15Lattice paths
159642
16Power digit sum
195261
17Number letter counts
129590
18Maximum path sum I
124412
19Counting Sundays
115756
20Factorial digit sum
170567
21Amicable numbers
124925
22Names scores
115267
23Non-abundant sums
88670
24Lexicographic permutations
98547
251000-digit Fibonacci number
133419
26Reciprocal cycles
71457
27Quadratic primes
74584
28Number spiral diagonals
93698
29Distinct powers
89761
30Digit fifth powers
94005
31Coin sums
72186
32Pandigital products
60608
33Digit cancelling fractions
61299
34Digit factorials
80667
35Circular primes
72759
36Double-base palindromes
76590
37Truncatable primes
62967
38Pandigital multiples
53667
39Integer right triangles
62458
40Champernowne's constant
68686
41Pandigital prime
58149
42Coded triangle numbers
64046
43Sub-string divisibility
50754
44Pentagon numbers
49328
45Triangular, pentagonal, and hexagonal
61020
46Goldbach's other conjecture
52168
47Distinct primes factors
49213
48Self powers
97653
49Prime permutations
49267
50Consecutive prime sum
53036