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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
798513
2Even Fibonacci numbers
639459
3Largest prime factor
457330
4Largest palindrome product
406000
5Smallest multiple
413640
6Sum square difference
416183
710001st prime
355964
8Largest product in a series
299519
9Special Pythagorean triplet
303194
10Summation of primes
277716
11Largest product in a grid
200608
12Highly divisible triangular number
187845
13Large sum
193368
14Longest Collatz sequence
193158
15Lattice paths
159637
16Power digit sum
195257
17Number letter counts
129588
18Maximum path sum I
124409
19Counting Sundays
115752
20Factorial digit sum
170560
21Amicable numbers
124923
22Names scores
115264
23Non-abundant sums
88668
24Lexicographic permutations
98546
251000-digit Fibonacci number
133418
26Reciprocal cycles
71453
27Quadratic primes
74582
28Number spiral diagonals
93697
29Distinct powers
89757
30Digit fifth powers
94001
31Coin sums
72181
32Pandigital products
60606
33Digit cancelling fractions
61299
34Digit factorials
80667
35Circular primes
72759
36Double-base palindromes
76589
37Truncatable primes
62966
38Pandigital multiples
53666
39Integer right triangles
62457
40Champernowne's constant
68686
41Pandigital prime
58149
42Coded triangle numbers
64046
43Sub-string divisibility
50754
44Pentagon numbers
49328
45Triangular, pentagonal, and hexagonal
61019
46Goldbach's other conjecture
52168
47Distinct primes factors
49212
48Self powers
97651
49Prime permutations
49267
50Consecutive prime sum
53035