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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
853364
2Even Fibonacci Numbers
682407
3Largest Prime Factor
514393
4Largest Palindrome Product
454694
5Smallest Multiple
441188
6Sum Square Difference
446167
710 001st Prime
388815
8Largest Product in a Series
331223
9Special Pythagorean Triplet
336732
10Summation of Primes
316104
11Largest Product in a Grid
236903
12Highly Divisible Triangular Number
233214
13Large Sum
233989
14Longest Collatz Sequence
238366
15Lattice Paths
202253
16Power Digit Sum
236701
17Number Letter Counts
169691
18Maximum Path Sum I
164069
19Counting Sundays
153859
20Factorial Digit Sum
207015
21Amicable Numbers
169166
22Names Scores
155887
23Non-Abundant Sums
128614
24Lexicographic Permutations
137742
25$1000$-digit Fibonacci Number
175376
26Reciprocal Cycles
104740
27Quadratic Primes
108243
28Number Spiral Diagonals
126965
29Distinct Powers
127925
30Digit Fifth Powers
132713
31Coin Sums
104498
32Pandigital Products
89093
33Digit Cancelling Fractions
88949
34Digit Factorials
115096
35Circular Primes
103110
36Double-base Palindromes
107668
37Truncatable Primes
91059
38Pandigital Multiples
78251
39Integer Right Triangles
89999
40Champernowne's Constant
97028
41Pandigital Prime
84383
42Coded Triangle Numbers
90016
43Sub-string Divisibility
74382
44Pentagon Numbers
72941
45Triangular, Pentagonal, and Hexagonal
86415
46Goldbach's Other Conjecture
76498
47Distinct Primes Factors
71964
48Self Powers
123090
49Prime Permutations
71566
50Consecutive Prime Sum
76672