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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
682800
3Largest Prime Factor
514613
4Largest Palindrome Product
454894
5Smallest Multiple
441376
6Sum Square Difference
446344
710 001st Prime
388988
8Largest Product in a Series
331307
9Special Pythagorean Triplet
336821
10Summation of Primes
316186
11Largest Product in a Grid
236938
12Highly Divisible Triangular Number
233237
13Large Sum
233996
14Longest Collatz Sequence
238377
15Lattice Paths
202261
16Power Digit Sum
236718
17Number Letter Counts
169673
18Maximum Path Sum I
164049
19Counting Sundays
153840
20Factorial Digit Sum
207002
21Amicable Numbers
169175
22Names Scores
155911
23Non-Abundant Sums
128594
24Lexicographic Permutations
137712
25$1000$-digit Fibonacci Number
175364
26Reciprocal Cycles
104711
27Quadratic Primes
108225
28Number Spiral Diagonals
126936
29Distinct Powers
127903
30Digit Fifth Powers
132684
31Coin Sums
104476
32Pandigital Products
89069
33Digit Cancelling Fractions
88921
34Digit Factorials
115069
35Circular Primes
103091
36Double-base Palindromes
107647
37Truncatable Primes
91045
38Pandigital Multiples
78238
39Integer Right Triangles
89978
40Champernowne's Constant
97011
41Pandigital Prime
84372
42Coded Triangle Numbers
89989
43Sub-string Divisibility
74370
44Pentagon Numbers
72916
45Triangular, Pentagonal, and Hexagonal
86400
46Goldbach's Other Conjecture
76480
47Distinct Primes Factors
71948
48Self Powers
123078
49Prime Permutations
71559
50Consecutive Prime Sum
76653