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Problem Archives

The problems archives table shows problems 1 to 1001. 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
854346
2Even Fibonacci Numbers
683083
3Largest Prime Factor
514782
4Largest Palindrome Product
455037
5Smallest Multiple
441494
6Sum Square Difference
446462
710 001st Prime
389078
8Largest Product in a Series
331379
9Special Pythagorean Triplet
336890
10Summation of Primes
316257
11Largest Product in a Grid
236960
12Highly Divisible Triangular Number
233267
13Large Sum
234024
14Longest Collatz Sequence
238397
15Lattice Paths
202259
16Power Digit Sum
236699
17Number Letter Counts
169662
18Maximum Path Sum I
164042
19Counting Sundays
153827
20Factorial Digit Sum
206991
21Amicable Numbers
169160
22Names Scores
155898
23Non-Abundant Sums
128574
24Lexicographic Permutations
137699
25$1000$-digit Fibonacci Number
175360
26Reciprocal Cycles
104697
27Quadratic Primes
108212
28Number Spiral Diagonals
126920
29Distinct Powers
127893
30Digit Fifth Powers
132669
31Coin Sums
104467
32Pandigital Products
89052
33Digit Cancelling Fractions
88912
34Digit Factorials
115059
35Circular Primes
103079
36Double-base Palindromes
107628
37Truncatable Primes
91036
38Pandigital Multiples
78218
39Integer Right Triangles
89967
40Champernowne's Constant
97010
41Pandigital Prime
84371
42Coded Triangle Numbers
89979
43Sub-string Divisibility
74363
44Pentagon Numbers
72914
45Triangular, Pentagonal, and Hexagonal
86393
46Goldbach's Other Conjecture
76470
47Distinct Primes Factors
71943
48Self Powers
123071
49Prime Permutations
71550
50Consecutive Prime Sum
76645