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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
851965
2Even Fibonacci Numbers
681356
3Largest Prime Factor
513788
4Largest Palindrome Product
454183
5Smallest Multiple
440703
6Sum Square Difference
445721
710 001st Prime
388427
8Largest Product in a Series
330989
9Special Pythagorean Triplet
336498
10Summation of Primes
315892
11Largest Product in a Grid
236851
12Highly Divisible Triangular Number
233152
13Large Sum
233916
14Longest Collatz Sequence
238304
15Lattice Paths
202252
16Power Digit Sum
236626
17Number Letter Counts
169710
18Maximum Path Sum I
164124
19Counting Sundays
153889
20Factorial Digit Sum
207049
21Amicable Numbers
169197
22Names Scores
155867
23Non-Abundant Sums
128669
24Lexicographic Permutations
137789
25$1000$-digit Fibonacci Number
175382
26Reciprocal Cycles
104798
27Quadratic Primes
108292
28Number Spiral Diagonals
127001
29Distinct Powers
127966
30Digit Fifth Powers
132767
31Coin Sums
104538
32Pandigital Products
89139
33Digit Cancelling Fractions
89008
34Digit Factorials
115154
35Circular Primes
103157
36Double-base Palindromes
107735
37Truncatable Primes
91109
38Pandigital Multiples
78293
39Integer Right Triangles
90052
40Champernowne's Constant
97072
41Pandigital Prime
84424
42Coded Triangle Numbers
90067
43Sub-string Divisibility
74435
44Pentagon Numbers
72985
45Triangular, Pentagonal, and Hexagonal
86481
46Goldbach's Other Conjecture
76538
47Distinct Primes Factors
72002
48Self Powers
123139
49Prime Permutations
71591
50Consecutive Prime Sum
76722