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Problem Archives

The problems archives table shows problems 1 to 997. 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
859403
2Even Fibonacci Numbers
686892
3Largest Prime Factor
517093
4Largest Palindrome Product
456922
5Smallest Multiple
443352
6Sum Square Difference
448284
710 001st Prime
390633
8Largest Product in a Series
332316
9Special Pythagorean Triplet
338003
10Summation of Primes
317206
11Largest Product in a Grid
237305
12Highly Divisible Triangular Number
233616
13Large Sum
234339
14Longest Collatz Sequence
238706
15Lattice Paths
202419
16Power Digit Sum
236965
17Number Letter Counts
169708
18Maximum Path Sum I
163986
19Counting Sundays
153786
20Factorial Digit Sum
207013
21Amicable Numbers
169097
22Names Scores
155806
23Non-Abundant Sums
128354
24Lexicographic Permutations
137548
25$1000$-digit Fibonacci Number
175367
26Reciprocal Cycles
104519
27Quadratic Primes
108020
28Number Spiral Diagonals
126746
29Distinct Powers
127763
30Digit Fifth Powers
132511
31Coin Sums
104324
32Pandigital Products
88896
33Digit Cancelling Fractions
88712
34Digit Factorials
114875
35Circular Primes
102937
36Double-base Palindromes
107448
37Truncatable Primes
90866
38Pandigital Multiples
78082
39Integer Right Triangles
89794
40Champernowne's Constant
96880
41Pandigital Prime
84242
42Coded Triangle Numbers
89789
43Sub-string Divisibility
74214
44Pentagon Numbers
72792
45Triangular, Pentagonal, and Hexagonal
86236
46Goldbach's Other Conjecture
76340
47Distinct Primes Factors
71814
48Self Powers
122996
49Prime Permutations
71422
50Consecutive Prime Sum
76532