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Problem Archives

The problems archives table shows problems 1 to 1008. 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
846953
2Even Fibonacci Numbers
677774
3Largest Prime Factor
511631
4Largest Palindrome Product
452464
5Smallest Multiple
438952
6Sum Square Difference
444045
710 001st Prime
387025
8Largest Product in a Series
330060
9Special Pythagorean Triplet
335496
10Summation of Primes
315048
11Largest Product in a Grid
236453
12Highly Divisible Triangular Number
232829
13Large Sum
233590
14Longest Collatz Sequence
237988
15Lattice Paths
202108
16Power Digit Sum
236386
17Number Letter Counts
169690
18Maximum Path Sum I
164111
19Counting Sundays
153919
20Factorial Digit Sum
207011
21Amicable Numbers
169234
22Names Scores
155947
23Non-Abundant Sums
128806
24Lexicographic Permutations
137908
25$1000$-digit Fibonacci Number
175407
26Reciprocal Cycles
104950
27Quadratic Primes
108433
28Number Spiral Diagonals
127171
29Distinct Powers
128100
30Digit Fifth Powers
132996
31Coin Sums
104637
32Pandigital Products
89260
33Digit Cancelling Fractions
89155
34Digit Factorials
115332
35Circular Primes
103264
36Double-base Palindromes
107917
37Truncatable Primes
91230
38Pandigital Multiples
78388
39Integer Right Triangles
90192
40Champernowne's Constant
97162
41Pandigital Prime
84513
42Coded Triangle Numbers
90229
43Sub-string Divisibility
74561
44Pentagon Numbers
73082
45Triangular, Pentagonal, and Hexagonal
86616
46Goldbach's Other Conjecture
76636
47Distinct Primes Factors
72095
48Self Powers
123223
49Prime Permutations
71687
50Consecutive Prime Sum
76824