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Problem Archives

The problems archives table shows problems 1 to 1004. 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
852900
2Even Fibonacci Numbers
682027
3Largest Prime Factor
514174
4Largest Palindrome Product
454522
5Smallest Multiple
441034
6Sum Square Difference
446022
710 001st Prime
388673
8Largest Product in a Series
331131
9Special Pythagorean Triplet
336637
10Summation of Primes
316018
11Largest Product in a Grid
236869
12Highly Divisible Triangular Number
233179
13Large Sum
233958
14Longest Collatz Sequence
238332
15Lattice Paths
202245
16Power Digit Sum
236682
17Number Letter Counts
169687
18Maximum Path Sum I
164073
19Counting Sundays
153864
20Factorial Digit Sum
207027
21Amicable Numbers
169180
22Names Scores
155891
23Non-Abundant Sums
128628
24Lexicographic Permutations
137749
25$1000$-digit Fibonacci Number
175366
26Reciprocal Cycles
104754
27Quadratic Primes
108259
28Number Spiral Diagonals
126974
29Distinct Powers
127945
30Digit Fifth Powers
132729
31Coin Sums
104504
32Pandigital Products
89103
33Digit Cancelling Fractions
88967
34Digit Factorials
115104
35Circular Primes
103115
36Double-base Palindromes
107687
37Truncatable Primes
91069
38Pandigital Multiples
78259
39Integer Right Triangles
90014
40Champernowne's Constant
97036
41Pandigital Prime
84388
42Coded Triangle Numbers
90025
43Sub-string Divisibility
74396
44Pentagon Numbers
72951
45Triangular, Pentagonal, and Hexagonal
86428
46Goldbach's Other Conjecture
76500
47Distinct Primes Factors
71975
48Self Powers
123102
49Prime Permutations
71576
50Consecutive Prime Sum
76680