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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
851928
2Even Fibonacci Numbers
681313
3Largest Prime Factor
513765
4Largest Palindrome Product
454165
5Smallest Multiple
440692
6Sum Square Difference
445702
710 001st Prime
388412
8Largest Product in a Series
330978
9Special Pythagorean Triplet
336484
10Summation of Primes
315882
11Largest Product in a Grid
236845
12Highly Divisible Triangular Number
233148
13Large Sum
233907
14Longest Collatz Sequence
238293
15Lattice Paths
202247
16Power Digit Sum
236615
17Number Letter Counts
169705
18Maximum Path Sum I
164120
19Counting Sundays
153884
20Factorial Digit Sum
207039
21Amicable Numbers
169193
22Names Scores
155864
23Non-Abundant Sums
128668
24Lexicographic Permutations
137787
25$1000$-digit Fibonacci Number
175377
26Reciprocal Cycles
104795
27Quadratic Primes
108291
28Number Spiral Diagonals
127000
29Distinct Powers
127963
30Digit Fifth Powers
132761
31Coin Sums
104538
32Pandigital Products
89138
33Digit Cancelling Fractions
89007
34Digit Factorials
115146
35Circular Primes
103152
36Double-base Palindromes
107728
37Truncatable Primes
91108
38Pandigital Multiples
78289
39Integer Right Triangles
90051
40Champernowne's Constant
97070
41Pandigital Prime
84424
42Coded Triangle Numbers
90066
43Sub-string Divisibility
74434
44Pentagon Numbers
72985
45Triangular, Pentagonal, and Hexagonal
86475
46Goldbach's Other Conjecture
76534
47Distinct Primes Factors
71998
48Self Powers
123132
49Prime Permutations
71588
50Consecutive Prime Sum
76716