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Problem Archives

The problems archives table shows problems 1 to 982. 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
1035865
2Even Fibonacci Numbers
823769
3Largest Prime Factor
593079
4Largest Palindrome Product
523556
5Smallest Multiple
525850
6Sum Square Difference
529603
710 001st Prime
452606
8Largest Product in a Series
379208
9Special Pythagorean Triplet
384372
10Summation of Primes
353274
11Largest Product in a Grid
253588
12Highly Divisible Triangular Number
240261
13Large Sum
245164
14Longest Collatz Sequence
245912
15Lattice Paths
203545
16Power Digit Sum
248047
17Number Letter Counts
165320
18Maximum Path Sum I
158397
19Counting Sundays
147030
20Factorial Digit Sum
214580
21Amicable Numbers
159689
22Names Scores
146648
23Non-Abundant Sums
115113
24Lexicographic Permutations
125791
25$1000$-digit Fibonacci Number
169333
26Reciprocal Cycles
93233
27Quadratic Primes
96718
28Number Spiral Diagonals
118000
29Distinct Powers
115922
30Digit Fifth Powers
120533
31Coin Sums
94442
32Pandigital Products
79326
33Digit Cancelling Fractions
79555
34Digit Factorials
103755
35Circular Primes
93517
36Double-base Palindromes
97593
37Truncatable Primes
81575
38Pandigital Multiples
70095
39Integer Right Triangles
80970
40Champernowne's Constant
88122
41Pandigital Prime
75739
42Coded Triangle Numbers
81974
43Sub-string Divisibility
66744
44Pentagon Numbers
65425
45Triangular, Pentagonal, and Hexagonal
78381
46Goldbach's Other Conjecture
68782
47Distinct Primes Factors
64758
48Self Powers
122035
49Prime Permutations
64577
50Consecutive Prime Sum
69653