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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
558906
2Even Fibonacci numbers
455328
3Largest prime factor
329099
4Largest palindrome product
295739
5Smallest multiple
307126
6Sum square difference
308872
710001st prime
264800
8Largest product in a series
227286
9Special Pythagorean triplet
227754
10Summation of primes
209321
11Largest product in a grid
153895
12Highly divisible triangular number
141957
13Large sum
148150
14Longest Collatz sequence
146576
15Lattice paths
121815
16Power digit sum
150117
17Number letter counts
99893
18Maximum path sum I
96790
19Counting Sundays
89590
20Factorial digit sum
133862
21Amicable numbers
96352
22Names scores
89316
23Non-abundant sums
68119
24Lexicographic permutations
76734
251000-digit Fibonacci number
103751
26Reciprocal cycles
55314
27Quadratic primes
58013
28Number spiral diagonals
74336
29Distinct powers
69514
30Digit fifth powers
73260
31Coin sums
55391
32Pandigital products
47138
33Digit cancelling fractions
48010
34Digit factorials
63353
35Circular primes
57509
36Double-base palindromes
60747
37Truncatable primes
49337
38Pandigital multiples
41971
39Integer right triangles
48679
40Champernowne's constant
53957
41Pandigital prime
45378
42Coded triangle numbers
50855
43Sub-string divisibility
39212
44Pentagon numbers
37992
45Triangular, pentagonal, and hexagonal
48291
46Goldbach's other conjecture
40283
47Distinct primes factors
38278
48Self powers
78602
49Prime permutations
38209
50Consecutive prime sum
41006