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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
864508
2Even Fibonacci Numbers
690723
3Largest Prime Factor
519332
4Largest Palindrome Product
458807
5Smallest Multiple
445216
6Sum Square Difference
450079
710 001st Prime
392059
8Largest Product in a Series
333191
9Special Pythagorean Triplet
338980
10Summation of Primes
318024
11Largest Product in a Grid
237673
12Highly Divisible Triangular Number
233905
13Large Sum
234636
14Longest Collatz Sequence
239009
15Lattice Paths
202453
16Power Digit Sum
237095
17Number Letter Counts
169664
18Maximum Path Sum I
163879
19Counting Sundays
153740
20Factorial Digit Sum
206964
21Amicable Numbers
168997
22Names Scores
155639
23Non-Abundant Sums
128131
24Lexicographic Permutations
137356
25$1000$-digit Fibonacci Number
175304
26Reciprocal Cycles
104271
27Quadratic Primes
107804
28Number Spiral Diagonals
126501
29Distinct Powers
127586
30Digit Fifth Powers
132244
31Coin Sums
104159
32Pandigital Products
88698
33Digit Cancelling Fractions
88482
34Digit Factorials
114597
35Circular Primes
102761
36Double-base Palindromes
107148
37Truncatable Primes
90666
38Pandigital Multiples
77910
39Integer Right Triangles
89577
40Champernowne's Constant
96707
41Pandigital Prime
84037
42Coded Triangle Numbers
89571
43Sub-string Divisibility
74014
44Pentagon Numbers
72620
45Triangular, Pentagonal, and Hexagonal
86025
46Goldbach's Other Conjecture
76166
47Distinct Primes Factors
71640
48Self Powers
122915
49Prime Permutations
71262
50Consecutive Prime Sum
76325