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Problem Archives

The problems archives table shows problems 1 to 998. 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
857896
2Even Fibonacci Numbers
685671
3Largest Prime Factor
516316
4Largest Palindrome Product
456342
5Smallest Multiple
442779
6Sum Square Difference
447573
710 001st Prime
390141
8Largest Product in a Series
332018
9Special Pythagorean Triplet
337614
10Summation of Primes
316889
11Largest Product in a Grid
237172
12Highly Divisible Triangular Number
233503
13Large Sum
234218
14Longest Collatz Sequence
238617
15Lattice Paths
202355
16Power Digit Sum
236885
17Number Letter Counts
169692
18Maximum Path Sum I
163995
19Counting Sundays
153778
20Factorial Digit Sum
207000
21Amicable Numbers
169088
22Names Scores
155828
23Non-Abundant Sums
128412
24Lexicographic Permutations
137589
25$1000$-digit Fibonacci Number
175339
26Reciprocal Cycles
104564
27Quadratic Primes
108076
28Number Spiral Diagonals
126792
29Distinct Powers
127795
30Digit Fifth Powers
132556
31Coin Sums
104353
32Pandigital Products
88943
33Digit Cancelling Fractions
88769
34Digit Factorials
114924
35Circular Primes
102976
36Double-base Palindromes
107500
37Truncatable Primes
90907
38Pandigital Multiples
78124
39Integer Right Triangles
89842
40Champernowne's Constant
96913
41Pandigital Prime
84274
42Coded Triangle Numbers
89837
43Sub-string Divisibility
74252
44Pentagon Numbers
72831
45Triangular, Pentagonal, and Hexagonal
86277
46Goldbach's Other Conjecture
76376
47Distinct Primes Factors
71857
48Self Powers
123016
49Prime Permutations
71463
50Consecutive Prime Sum
76563