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Problems Archives

The problems archives table shows problems 1 to 548. 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
560169
2Even Fibonacci numbers
456311
3Largest prime factor
329817
4Largest palindrome product
296404
5Smallest multiple
307740
6Sum square difference
309471
710001st prime
265303
8Largest product in a series
227702
9Special Pythagorean triplet
228161
10Summation of primes
209708
11Largest product in a grid
154173
12Highly divisible triangular number
142217
13Large sum
148430
14Longest Collatz sequence
146835
15Lattice paths
122014
16Power digit sum
150379
17Number letter counts
100059
18Maximum path sum I
96943
19Counting Sundays
89723
20Factorial digit sum
134071
21Amicable numbers
96520
22Names scores
89463
23Non-abundant sums
68266
24Lexicographic permutations
76874
251000-digit Fibonacci number
103930
26Reciprocal cycles
55417
27Quadratic primes
58126
28Number spiral diagonals
74458
29Distinct powers
69652
30Digit fifth powers
73387
31Coin sums
55497
32Pandigital products
47238
33Digit cancelling fractions
48095
34Digit factorials
63460
35Circular primes
57605
36Double-base palindromes
60852
37Truncatable primes
49432
38Pandigital multiples
42036
39Integer right triangles
48770
40Champernowne's constant
54046
41Pandigital prime
45460
42Coded triangle numbers
50927
43Sub-string divisibility
39277
44Pentagon numbers
38047
45Triangular, pentagonal, and hexagonal
48353
46Goldbach's other conjecture
40345
47Distinct primes factors
38342
48Self powers
78714
49Prime permutations
38265
50Consecutive prime sum
41072