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Problem Archives

The problems archives table shows problems 1 to 1005. 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
850023
2Even Fibonacci Numbers
679966
3Largest Prime Factor
512950
4Largest Palindrome Product
453553
5Smallest Multiple
440036
6Sum Square Difference
445099
710 001st Prime
387874
8Largest Product in a Series
330653
9Special Pythagorean Triplet
336093
10Summation of Primes
315545
11Largest Product in a Grid
236704
12Highly Divisible Triangular Number
233028
13Large Sum
233803
14Longest Collatz Sequence
238194
15Lattice Paths
202196
16Power Digit Sum
236531
17Number Letter Counts
169704
18Maximum Path Sum I
164115
19Counting Sundays
153888
20Factorial Digit Sum
207039
21Amicable Numbers
169200
22Names Scores
155882
23Non-Abundant Sums
128720
24Lexicographic Permutations
137828
25$1000$-digit Fibonacci Number
175383
26Reciprocal Cycles
104844
27Quadratic Primes
108335
28Number Spiral Diagonals
127064
29Distinct Powers
127997
30Digit Fifth Powers
132844
31Coin Sums
104581
32Pandigital Products
89171
33Digit Cancelling Fractions
89054
34Digit Factorials
115208
35Circular Primes
103188
36Double-base Palindromes
107784
37Truncatable Primes
91146
38Pandigital Multiples
78320
39Integer Right Triangles
90094
40Champernowne's Constant
97114
41Pandigital Prime
84444
42Coded Triangle Numbers
90117
43Sub-string Divisibility
74469
44Pentagon Numbers
73008
45Triangular, Pentagonal, and Hexagonal
86530
46Goldbach's Other Conjecture
76575
47Distinct Primes Factors
72027
48Self Powers
123165
49Prime Permutations
71619
50Consecutive Prime Sum
76755