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Problem Archives

The problems archives table shows problems 1 to 1006. 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
848909
2Even Fibonacci Numbers
679180
3Largest Prime Factor
512496
4Largest Palindrome Product
453181
5Smallest Multiple
439659
6Sum Square Difference
444702
710 001st Prime
387552
8Largest Product in a Series
330421
9Special Pythagorean Triplet
335854
10Summation of Primes
315357
11Largest Product in a Grid
236626
12Highly Divisible Triangular Number
232953
13Large Sum
233732
14Longest Collatz Sequence
238120
15Lattice Paths
202164
16Power Digit Sum
236460
17Number Letter Counts
169699
18Maximum Path Sum I
164108
19Counting Sundays
153896
20Factorial Digit Sum
207020
21Amicable Numbers
169211
22Names Scores
155898
23Non-Abundant Sums
128759
24Lexicographic Permutations
137851
25$1000$-digit Fibonacci Number
175365
26Reciprocal Cycles
104876
27Quadratic Primes
108373
28Number Spiral Diagonals
127101
29Distinct Powers
128039
30Digit Fifth Powers
132904
31Coin Sums
104609
32Pandigital Products
89205
33Digit Cancelling Fractions
89094
34Digit Factorials
115255
35Circular Primes
103216
36Double-base Palindromes
107834
37Truncatable Primes
91184
38Pandigital Multiples
78348
39Integer Right Triangles
90137
40Champernowne's Constant
97137
41Pandigital Prime
84470
42Coded Triangle Numbers
90163
43Sub-string Divisibility
74504
44Pentagon Numbers
73030
45Triangular, Pentagonal, and Hexagonal
86555
46Goldbach's Other Conjecture
76595
47Distinct Primes Factors
72055
48Self Powers
123176
49Prime Permutations
71648
50Consecutive Prime Sum
76789