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Problems Archives

The problems archives table shows problems 1 to 501. 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
453636
2Even Fibonacci numbers
372619
3Largest prime factor
271092
4Largest palindrome product
245240
5Smallest multiple
257918
6Sum square difference
259777
710001st prime
222690
8Largest product in a series
193939
9Special Pythagorean triplet
193133
10Summation of primes
177306
11Largest product in a grid
131810
12Highly divisible triangular number
120406
13Large sum
126952
14Longest Collatz sequence
124940
15Lattice paths
104154
16Power digit sum
129501
17Number letter counts
85663
18Maximum path sum I
83450
19Counting Sundays
77170
20Factorial digit sum
116774
21Amicable numbers
82918
22Names scores
77297
23Non-abundant sums
58479
24Lexicographic permutations
66533
251000-digit Fibonacci number
90127
26Reciprocal cycles
47689
27Quadratic primes
50187
28Number spiral diagonals
65450
29Distinct powers
60210
30Digit fifth powers
63694
31Coin sums
47674
32Pandigital products
40763
33Digit cancelling fractions
41840
34Digit factorials
55370
35Circular primes
50453
36Double-base palindromes
53425
37Truncatable primes
42933
38Pandigital multiples
36503
39Integer right triangles
42322
40Champernowne's constant
47140
41Pandigital prime
39503
42Coded triangle numbers
44785
43Sub-string divisibility
33922
44Pentagon numbers
32695
45Triangular, pentagonal, and hexagonal
42496
46Goldbach's other conjecture
34856
47Distinct primes factors
33165
48Self powers
70077
49Prime permutations
33038
50Consecutive prime sum
35442