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Problem Archives

The problems archives table shows problems 1 to 997. 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
860882
2Even Fibonacci Numbers
688014
3Largest Prime Factor
517765
4Largest Palindrome Product
457489
5Smallest Multiple
443889
6Sum Square Difference
448819
710 001st Prime
391063
8Largest Product in a Series
332581
9Special Pythagorean Triplet
338311
10Summation of Primes
317472
11Largest Product in a Grid
237452
12Highly Divisible Triangular Number
233724
13Large Sum
234441
14Longest Collatz Sequence
238833
15Lattice Paths
202458
16Power Digit Sum
237036
17Number Letter Counts
169730
18Maximum Path Sum I
163974
19Counting Sundays
153791
20Factorial Digit Sum
207011
21Amicable Numbers
169079
22Names Scores
155780
23Non-Abundant Sums
128295
24Lexicographic Permutations
137494
25$1000$-digit Fibonacci Number
175360
26Reciprocal Cycles
104457
27Quadratic Primes
107975
28Number Spiral Diagonals
126690
29Distinct Powers
127717
30Digit Fifth Powers
132450
31Coin Sums
104294
32Pandigital Products
88847
33Digit Cancelling Fractions
88662
34Digit Factorials
114802
35Circular Primes
102887
36Double-base Palindromes
107374
37Truncatable Primes
90822
38Pandigital Multiples
78045
39Integer Right Triangles
89750
40Champernowne's Constant
96843
41Pandigital Prime
84196
42Coded Triangle Numbers
89737
43Sub-string Divisibility
74157
44Pentagon Numbers
72743
45Triangular, Pentagonal, and Hexagonal
86186
46Goldbach's Other Conjecture
76295
47Distinct Primes Factors
71783
48Self Powers
122976
49Prime Permutations
71387
50Consecutive Prime Sum
76489