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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
851931
2Even Fibonacci Numbers
681349
3Largest Prime Factor
513786
4Largest Palindrome Product
454179
5Smallest Multiple
440703
6Sum Square Difference
445718
710 001st Prime
388424
8Largest Product in a Series
330987
9Special Pythagorean Triplet
336495
10Summation of Primes
315891
11Largest Product in a Grid
236850
12Highly Divisible Triangular Number
233152
13Large Sum
233916
14Longest Collatz Sequence
238302
15Lattice Paths
202252
16Power Digit Sum
236623
17Number Letter Counts
169709
18Maximum Path Sum I
164123
19Counting Sundays
153886
20Factorial Digit Sum
207049
21Amicable Numbers
169197
22Names Scores
155866
23Non-Abundant Sums
128669
24Lexicographic Permutations
137789
25$1000$-digit Fibonacci Number
175382
26Reciprocal Cycles
104796
27Quadratic Primes
108292
28Number Spiral Diagonals
127001
29Distinct Powers
127965
30Digit Fifth Powers
132766
31Coin Sums
104538
32Pandigital Products
89139
33Digit Cancelling Fractions
89008
34Digit Factorials
115151
35Circular Primes
103156
36Double-base Palindromes
107733
37Truncatable Primes
91109
38Pandigital Multiples
78293
39Integer Right Triangles
90051
40Champernowne's Constant
97072
41Pandigital Prime
84424
42Coded Triangle Numbers
90067
43Sub-string Divisibility
74435
44Pentagon Numbers
72985
45Triangular, Pentagonal, and Hexagonal
86480
46Goldbach's Other Conjecture
76538
47Distinct Primes Factors
72002
48Self Powers
123139
49Prime Permutations
71590
50Consecutive Prime Sum
76719