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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
850289
2Even Fibonacci Numbers
680159
3Largest Prime Factor
513077
4Largest Palindrome Product
453665
5Smallest Multiple
440145
6Sum Square Difference
445213
710 001st Prime
387970
8Largest Product in a Series
330720
9Special Pythagorean Triplet
336163
10Summation of Primes
315615
11Largest Product in a Grid
236739
12Highly Divisible Triangular Number
233059
13Large Sum
233832
14Longest Collatz Sequence
238231
15Lattice Paths
202220
16Power Digit Sum
236561
17Number Letter Counts
169718
18Maximum Path Sum I
164127
19Counting Sundays
153897
20Factorial Digit Sum
207059
21Amicable Numbers
169209
22Names Scores
155893
23Non-Abundant Sums
128724
24Lexicographic Permutations
137830
25$1000$-digit Fibonacci Number
175397
26Reciprocal Cycles
104842
27Quadratic Primes
108335
28Number Spiral Diagonals
127063
29Distinct Powers
127999
30Digit Fifth Powers
132844
31Coin Sums
104583
32Pandigital Products
89171
33Digit Cancelling Fractions
89054
34Digit Factorials
115207
35Circular Primes
103189
36Double-base Palindromes
107782
37Truncatable Primes
91146
38Pandigital Multiples
78320
39Integer Right Triangles
90095
40Champernowne's Constant
97114
41Pandigital Prime
84445
42Coded Triangle Numbers
90115
43Sub-string Divisibility
74469
44Pentagon Numbers
73009
45Triangular, Pentagonal, and Hexagonal
86526
46Goldbach's Other Conjecture
76573
47Distinct Primes Factors
72028
48Self Powers
123164
49Prime Permutations
71618
50Consecutive Prime Sum
76755