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Problems Archives

The problems archives table shows problems 1 to 502. 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
453809
2Even Fibonacci numbers
372771
3Largest prime factor
271205
4Largest palindrome product
245330
5Smallest multiple
258011
6Sum square difference
259862
710001st prime
222779
8Largest product in a series
194011
9Special Pythagorean triplet
193198
10Summation of primes
177359
11Largest product in a grid
131853
12Highly divisible triangular number
120440
13Large sum
126984
14Longest Collatz sequence
124984
15Lattice paths
104188
16Power digit sum
129535
17Number letter counts
85683
18Maximum path sum I
83471
19Counting Sundays
77200
20Factorial digit sum
116800
21Amicable numbers
82937
22Names scores
77321
23Non-abundant sums
58503
24Lexicographic permutations
66547
251000-digit Fibonacci number
90154
26Reciprocal cycles
47705
27Quadratic primes
50206
28Number spiral diagonals
65469
29Distinct powers
60232
30Digit fifth powers
63713
31Coin sums
47684
32Pandigital products
40775
33Digit cancelling fractions
41853
34Digit factorials
55386
35Circular primes
50471
36Double-base palindromes
53446
37Truncatable primes
42948
38Pandigital multiples
36515
39Integer right triangles
42340
40Champernowne's constant
47158
41Pandigital prime
39514
42Coded triangle numbers
44800
43Sub-string divisibility
33933
44Pentagon numbers
32707
45Triangular, pentagonal, and hexagonal
42509
46Goldbach's other conjecture
34870
47Distinct primes factors
33179
48Self powers
70091
49Prime permutations
33046
50Consecutive prime sum
35451