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Problems Archives

The problems archives table shows problems 1 to 619. 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
760528
2Even Fibonacci numbers
610845
3Largest prime factor
437362
4Largest palindrome product
389203
5Smallest multiple
397351
6Sum square difference
399736
710001st prime
342157
8Largest product in a series
288913
9Special Pythagorean triplet
291861
10Summation of primes
267693
11Largest product in a grid
193978
12Highly divisible triangular number
181300
13Large sum
186981
14Longest Collatz sequence
186528
15Lattice paths
154209
16Power digit sum
188664
17Number letter counts
125451
18Maximum path sum I
120567
19Counting Sundays
112053
20Factorial digit sum
165305
21Amicable numbers
120977
22Names scores
111689
23Non-abundant sums
85831
24Lexicographic permutations
95396
251000-digit Fibonacci number
129116
26Reciprocal cycles
69220
27Quadratic primes
72336
28Number spiral diagonals
90936
29Distinct powers
86943
30Digit fifth powers
91107
31Coin sums
69717
32Pandigital products
58750
33Digit cancelling fractions
59471
34Digit factorials
78269
35Circular primes
70586
36Double-base palindromes
74380
37Truncatable primes
61060
38Pandigital multiples
52023
39Integer right triangles
60541
40Champernowne's constant
66682
41Pandigital prime
56342
42Coded triangle numbers
62253
43Sub-string divisibility
49136
44Pentagon numbers
47757
45Triangular, pentagonal, and hexagonal
59217
46Goldbach's other conjecture
50512
47Distinct primes factors
47728
48Self powers
94980
49Prime permutations
47712
50Consecutive prime sum
51386