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Problem Archives

The problems archives table shows problems 1 to 973. 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
1035929
2Even Fibonacci Numbers
823828
3Largest Prime Factor
593124
4Largest Palindrome Product
523651
5Smallest Multiple
525899
6Sum Square Difference
529660
710 001st Prime
452622
8Largest Product in a Series
379262
9Special Pythagorean Triplet
384417
10Summation of Primes
353304
11Largest Product in a Grid
253604
12Highly Divisible Triangular Number
240277
13Large Sum
245169
14Longest Collatz Sequence
245931
15Lattice Paths
203554
16Power Digit Sum
248057
17Number Letter Counts
165308
18Maximum Path Sum I
158377
19Counting Sundays
147006
20Factorial Digit Sum
214581
21Amicable Numbers
159669
22Names Scores
146630
23Non-Abundant Sums
115083
24Lexicographic Permutations
125758
25$1000$-digit Fibonacci Number
169329
26Reciprocal Cycles
93157
27Quadratic Primes
96653
28Number Spiral Diagonals
117943
29Distinct Powers
115869
30Digit Fifth Powers
120473
31Coin Sums
94370
32Pandigital Products
79240
33Digit Cancelling Fractions
79467
34Digit Factorials
103690
35Circular Primes
93450
36Double-base Palindromes
97522
37Truncatable Primes
81499
38Pandigital Multiples
70008
39Integer Right Triangles
80886
40Champernowne's Constant
88041
41Pandigital Prime
75653
42Coded Triangle Numbers
81882
43Sub-string Divisibility
66653
44Pentagon Numbers
65329
45Triangular, Pentagonal, and Hexagonal
78277
46Goldbach's Other Conjecture
68687
47Distinct Primes Factors
64661
48Self Powers
121960
49Prime Permutations
64482
50Consecutive Prime Sum
69560