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Problem Archives

The problems archives table shows problems 1 to 997. 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
862171
2Even Fibonacci Numbers
689005
3Largest Prime Factor
518366
4Largest Palindrome Product
458010
5Smallest Multiple
444427
6Sum Square Difference
449326
710 001st Prime
391469
8Largest Product in a Series
332830
9Special Pythagorean Triplet
338590
10Summation of Primes
317725
11Largest Product in a Grid
237587
12Highly Divisible Triangular Number
233837
13Large Sum
234526
14Longest Collatz Sequence
238927
15Lattice Paths
202503
16Power Digit Sum
237075
17Number Letter Counts
169723
18Maximum Path Sum I
163968
19Counting Sundays
153805
20Factorial Digit Sum
207023
21Amicable Numbers
169075
22Names Scores
155744
23Non-Abundant Sums
128238
24Lexicographic Permutations
137449
25$1000$-digit Fibonacci Number
175351
26Reciprocal Cycles
104398
27Quadratic Primes
107916
28Number Spiral Diagonals
126630
29Distinct Powers
127681
30Digit Fifth Powers
132406
31Coin Sums
104251
32Pandigital Products
88809
33Digit Cancelling Fractions
88610
34Digit Factorials
114751
35Circular Primes
102865
36Double-base Palindromes
107314
37Truncatable Primes
90784
38Pandigital Multiples
78010
39Integer Right Triangles
89710
40Champernowne's Constant
96819
41Pandigital Prime
84154
42Coded Triangle Numbers
89696
43Sub-string Divisibility
74116
44Pentagon Numbers
72710
45Triangular, Pentagonal, and Hexagonal
86138
46Goldbach's Other Conjecture
76247
47Distinct Primes Factors
71738
48Self Powers
122959
49Prime Permutations
71350
50Consecutive Prime Sum
76438