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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
851970
2Even Fibonacci Numbers
681360
3Largest Prime Factor
513793
4Largest Palindrome Product
454185
5Smallest Multiple
440703
6Sum Square Difference
445724
710 001st Prime
388428
8Largest Product in a Series
330991
9Special Pythagorean Triplet
336501
10Summation of Primes
315893
11Largest Product in a Grid
236851
12Highly Divisible Triangular Number
233153
13Large Sum
233918
14Longest Collatz Sequence
238306
15Lattice Paths
202253
16Power Digit Sum
236628
17Number Letter Counts
169711
18Maximum Path Sum I
164127
19Counting Sundays
153889
20Factorial Digit Sum
207051
21Amicable Numbers
169198
22Names Scores
155868
23Non-Abundant Sums
128670
24Lexicographic Permutations
137790
25$1000$-digit Fibonacci Number
175382
26Reciprocal Cycles
104798
27Quadratic Primes
108292
28Number Spiral Diagonals
127001
29Distinct Powers
127966
30Digit Fifth Powers
132768
31Coin Sums
104538
32Pandigital Products
89139
33Digit Cancelling Fractions
89008
34Digit Factorials
115154
35Circular Primes
103159
36Double-base Palindromes
107737
37Truncatable Primes
91110
38Pandigital Multiples
78293
39Integer Right Triangles
90052
40Champernowne's Constant
97072
41Pandigital Prime
84425
42Coded Triangle Numbers
90067
43Sub-string Divisibility
74435
44Pentagon Numbers
72985
45Triangular, Pentagonal, and Hexagonal
86482
46Goldbach's Other Conjecture
76538
47Distinct Primes Factors
72003
48Self Powers
123139
49Prime Permutations
71591
50Consecutive Prime Sum
76722