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Problem Archives

The problems archives table shows problems 1 to 1003. 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
853485
2Even Fibonacci Numbers
682513
3Largest Prime Factor
514453
4Largest Palindrome Product
454758
5Smallest Multiple
441241
6Sum Square Difference
446205
710 001st Prime
388870
8Largest Product in a Series
331249
9Special Pythagorean Triplet
336762
10Summation of Primes
316132
11Largest Product in a Grid
236917
12Highly Divisible Triangular Number
233227
13Large Sum
233985
14Longest Collatz Sequence
238369
15Lattice Paths
202260
16Power Digit Sum
236725
17Number Letter Counts
169689
18Maximum Path Sum I
164064
19Counting Sundays
153853
20Factorial Digit Sum
207007
21Amicable Numbers
169172
22Names Scores
155909
23Non-Abundant Sums
128605
24Lexicographic Permutations
137730
25$1000$-digit Fibonacci Number
175364
26Reciprocal Cycles
104727
27Quadratic Primes
108235
28Number Spiral Diagonals
126953
29Distinct Powers
127916
30Digit Fifth Powers
132704
31Coin Sums
104493
32Pandigital Products
89088
33Digit Cancelling Fractions
88940
34Digit Factorials
115086
35Circular Primes
103103
36Double-base Palindromes
107660
37Truncatable Primes
91054
38Pandigital Multiples
78247
39Integer Right Triangles
89986
40Champernowne's Constant
97016
41Pandigital Prime
84375
42Coded Triangle Numbers
90003
43Sub-string Divisibility
74375
44Pentagon Numbers
72924
45Triangular, Pentagonal, and Hexagonal
86406
46Goldbach's Other Conjecture
76487
47Distinct Primes Factors
71955
48Self Powers
123084
49Prime Permutations
71562
50Consecutive Prime Sum
76665