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Problems Archives

The problems archives table shows problems 1 to 615. 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
746079
2Even Fibonacci numbers
599761
3Largest prime factor
429608
4Largest palindrome product
382599
5Smallest multiple
391100
6Sum square difference
393337
710001st prime
336712
8Largest product in a series
284585
9Special Pythagorean triplet
287351
10Summation of primes
263579
11Largest product in a grid
191217
12Highly divisible triangular number
178508
13Large sum
184304
14Longest Collatz sequence
183804
15Lattice paths
151929
16Power digit sum
185964
17Number letter counts
123738
18Maximum path sum I
118932
19Counting Sundays
110542
20Factorial digit sum
163086
21Amicable numbers
119165
22Names scores
110163
23Non-abundant sums
84616
24Lexicographic permutations
94087
251000-digit Fibonacci number
127335
26Reciprocal cycles
68251
27Quadratic primes
71384
28Number spiral diagonals
89850
29Distinct powers
85740
30Digit fifth powers
89866
31Coin sums
68660
32Pandigital products
57979
33Digit cancelling fractions
58634
34Digit factorials
77224
35Circular primes
69684
36Double-base palindromes
73417
37Truncatable primes
60217
38Pandigital multiples
51313
39Integer right triangles
59662
40Champernowne's constant
65805
41Pandigital prime
55566
42Coded triangle numbers
61454
43Sub-string divisibility
48470
44Pentagon numbers
47048
45Triangular, pentagonal, and hexagonal
58432
46Goldbach's other conjecture
49798
47Distinct primes factors
47063
48Self powers
93732
49Prime permutations
47048
50Consecutive prime sum
50663