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Problem Archives

The problems archives table shows problems 1 to 997. If you would like to tackle the 10 most recently published problems, go to Recent problems.



ID

 Title
Solved By
1Multiples of 3 or 5
860592
2Even Fibonacci Numbers
687795
3Largest Prime Factor
517623
4Largest Palindrome Product
457375
5Smallest Multiple
443777
6Sum Square Difference
448713
710 001st Prime
390977
8Largest Product in a Series
332533
9Special Pythagorean Triplet
338257
10Summation of Primes
317414
11Largest Product in a Grid
237431
12Highly Divisible Triangular Number
233701
13Large Sum
234434
14Longest Collatz Sequence
238816
15Lattice Paths
202476
16Power Digit Sum
237030
17Number Letter Counts
169727
18Maximum Path Sum I
163982
19Counting Sundays
153788
20Factorial Digit Sum
207023
21Amicable Numbers
169080
22Names Scores
155788
23Non-Abundant Sums
128313
24Lexicographic Permutations
137520
25$1000$-digit Fibonacci Number
175361
26Reciprocal Cycles
104482
27Quadratic Primes
107985
28Number Spiral Diagonals
126704
29Distinct Powers
127736
30Digit Fifth Powers
132463
31Coin Sums
104301
32Pandigital Products
88862
33Digit Cancelling Fractions
88677
34Digit Factorials
114827
35Circular Primes
102905
36Double-base Palindromes
107391
37Truncatable Primes
90835
38Pandigital Multiples
78057
39Integer Right Triangles
89759
40Champernowne's Constant
96852
41Pandigital Prime
84210
42Coded Triangle Numbers
89749
43Sub-string Divisibility
74168
44Pentagon Numbers
72757
45Triangular, Pentagonal, and Hexagonal
86196
46Goldbach's Other Conjecture
76312
47Distinct Primes Factors
71790
48Self Powers
122978
49Prime Permutations
71397
50Consecutive Prime Sum
76493