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Problem Archives

The problems archives table shows problems 1 to 1007. 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
848175
2Even Fibonacci Numbers
678655
3Largest Prime Factor
512177
4Largest Palindrome Product
452906
5Smallest Multiple
439386
6Sum Square Difference
444445
710 001st Prime
387361
8Largest Product in a Series
330286
9Special Pythagorean Triplet
335720
10Summation of Primes
315236
11Largest Product in a Grid
236554
12Highly Divisible Triangular Number
232896
13Large Sum
233679
14Longest Collatz Sequence
238061
15Lattice Paths
202126
16Power Digit Sum
236420
17Number Letter Counts
169694
18Maximum Path Sum I
164098
19Counting Sundays
153898
20Factorial Digit Sum
207009
21Amicable Numbers
169219
22Names Scores
155905
23Non-Abundant Sums
128775
24Lexicographic Permutations
137874
25$1000$-digit Fibonacci Number
175374
26Reciprocal Cycles
104901
27Quadratic Primes
108394
28Number Spiral Diagonals
127125
29Distinct Powers
128051
30Digit Fifth Powers
132929
31Coin Sums
104613
32Pandigital Products
89220
33Digit Cancelling Fractions
89118
34Digit Factorials
115277
35Circular Primes
103224
36Double-base Palindromes
107867
37Truncatable Primes
91197
38Pandigital Multiples
78360
39Integer Right Triangles
90155
40Champernowne's Constant
97138
41Pandigital Prime
84482
42Coded Triangle Numbers
90183
43Sub-string Divisibility
74529
44Pentagon Numbers
73050
45Triangular, Pentagonal, and Hexagonal
86578
46Goldbach's Other Conjecture
76611
47Distinct Primes Factors
72067
48Self Powers
123195
49Prime Permutations
71668
50Consecutive Prime Sum
76799