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Problem Archives

The problems archives table shows problems 1 to 1003. 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
853911
2Even Fibonacci Numbers
682790
3Largest Prime Factor
514610
4Largest Palindrome Product
454893
5Smallest Multiple
441374
6Sum Square Difference
446340
710 001st Prime
388985
8Largest Product in a Series
331305
9Special Pythagorean Triplet
336820
10Summation of Primes
316185
11Largest Product in a Grid
236937
12Highly Divisible Triangular Number
233235
13Large Sum
233993
14Longest Collatz Sequence
238376
15Lattice Paths
202259
16Power Digit Sum
236715
17Number Letter Counts
169669
18Maximum Path Sum I
164049
19Counting Sundays
153839
20Factorial Digit Sum
206999
21Amicable Numbers
169174
22Names Scores
155910
23Non-Abundant Sums
128593
24Lexicographic Permutations
137710
25$1000$-digit Fibonacci Number
175359
26Reciprocal Cycles
104710
27Quadratic Primes
108225
28Number Spiral Diagonals
126934
29Distinct Powers
127903
30Digit Fifth Powers
132683
31Coin Sums
104476
32Pandigital Products
89069
33Digit Cancelling Fractions
88921
34Digit Factorials
115069
35Circular Primes
103091
36Double-base Palindromes
107647
37Truncatable Primes
91044
38Pandigital Multiples
78237
39Integer Right Triangles
89976
40Champernowne's Constant
97011
41Pandigital Prime
84372
42Coded Triangle Numbers
89989
43Sub-string Divisibility
74369
44Pentagon Numbers
72916
45Triangular, Pentagonal, and Hexagonal
86400
46Goldbach's Other Conjecture
76480
47Distinct Primes Factors
71947
48Self Powers
123078
49Prime Permutations
71559
50Consecutive Prime Sum
76652