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Problems Archives

The problems archives table shows problems 1 to 576. 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
630152
2Even Fibonacci numbers
510689
3Largest prime factor
367351
4Largest palindrome product
328972
5Smallest multiple
339475
6Sum square difference
341430
710001st prime
292567
8Largest product in a series
249261
9Special Pythagorean triplet
250782
10Summation of primes
230287
11Largest product in a grid
168502
12Highly divisible triangular number
156352
13Large sum
162247
14Longest Collatz sequence
161006
15Lattice paths
133546
16Power digit sum
164040
17Number letter counts
109330
18Maximum path sum I
105543
19Counting Sundays
97903
20Factorial digit sum
145303
21Amicable numbers
105329
22Names scores
97538
23Non-abundant sums
74637
24Lexicographic permutations
83599
251000-digit Fibonacci number
112997
26Reciprocal cycles
60469
27Quadratic primes
63308
28Number spiral diagonals
80417
29Distinct powers
75934
30Digit fifth powers
79785
31Coin sums
60691
32Pandigital products
51408
33Digit cancelling fractions
52282
34Digit factorials
68823
35Circular primes
62301
36Double-base palindromes
65615
37Truncatable primes
53627
38Pandigital multiples
45645
39Integer right triangles
52971
40Champernowne's constant
58633
41Pandigital prime
49397
42Coded triangle numbers
54997
43Sub-string divisibility
42855
44Pentagon numbers
41543
45Triangular, pentagonal, and hexagonal
52243
46Goldbach's other conjecture
44012
47Distinct primes factors
41742
48Self powers
84481
49Prime permutations
41701
50Consecutive prime sum
44786