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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
853377
2Even Fibonacci Numbers
682418
3Largest Prime Factor
514396
4Largest Palindrome Product
454703
5Smallest Multiple
441194
6Sum Square Difference
446189
710 001st Prime
388819
8Largest Product in a Series
331227
9Special Pythagorean Triplet
336737
10Summation of Primes
316108
11Largest Product in a Grid
236906
12Highly Divisible Triangular Number
233216
13Large Sum
233990
14Longest Collatz Sequence
238369
15Lattice Paths
202256
16Power Digit Sum
236715
17Number Letter Counts
169692
18Maximum Path Sum I
164071
19Counting Sundays
153862
20Factorial Digit Sum
207027
21Amicable Numbers
169167
22Names Scores
155888
23Non-Abundant Sums
128615
24Lexicographic Permutations
137746
25$1000$-digit Fibonacci Number
175376
26Reciprocal Cycles
104741
27Quadratic Primes
108244
28Number Spiral Diagonals
126966
29Distinct Powers
127925
30Digit Fifth Powers
132715
31Coin Sums
104498
32Pandigital Products
89093
33Digit Cancelling Fractions
88950
34Digit Factorials
115096
35Circular Primes
103110
36Double-base Palindromes
107670
37Truncatable Primes
91059
38Pandigital Multiples
78251
39Integer Right Triangles
90000
40Champernowne's Constant
97028
41Pandigital Prime
84383
42Coded Triangle Numbers
90016
43Sub-string Divisibility
74383
44Pentagon Numbers
72941
45Triangular, Pentagonal, and Hexagonal
86415
46Goldbach's Other Conjecture
76499
47Distinct Primes Factors
71967
48Self Powers
123090
49Prime Permutations
71566
50Consecutive Prime Sum
76673