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Problem Archives

The problems archives table shows problems 1 to 1000. 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
856556
2Even Fibonacci Numbers
684708
3Largest Prime Factor
515746
4Largest Palindrome Product
455863
5Smallest Multiple
442297
6Sum Square Difference
447243
710 001st Prime
389757
8Largest Product in a Series
331792
9Special Pythagorean Triplet
337351
10Summation of Primes
316661
11Largest Product in a Grid
237081
12Highly Divisible Triangular Number
233427
13Large Sum
234162
14Longest Collatz Sequence
238536
15Lattice Paths
202322
16Power Digit Sum
236832
17Number Letter Counts
169686
18Maximum Path Sum I
164020
19Counting Sundays
153791
20Factorial Digit Sum
207003
21Amicable Numbers
169125
22Names Scores
155857
23Non-Abundant Sums
128474
24Lexicographic Permutations
137628
25$1000$-digit Fibonacci Number
175344
26Reciprocal Cycles
104605
27Quadratic Primes
108121
28Number Spiral Diagonals
126840
29Distinct Powers
127842
30Digit Fifth Powers
132601
31Coin Sums
104393
32Pandigital Products
88982
33Digit Cancelling Fractions
88825
34Digit Factorials
114978
35Circular Primes
103011
36Double-base Palindromes
107547
37Truncatable Primes
90946
38Pandigital Multiples
78159
39Integer Right Triangles
89890
40Champernowne's Constant
96955
41Pandigital Prime
84306
42Coded Triangle Numbers
89891
43Sub-string Divisibility
74293
44Pentagon Numbers
72856
45Triangular, Pentagonal, and Hexagonal
86316
46Goldbach's Other Conjecture
76406
47Distinct Primes Factors
71890
48Self Powers
123047
49Prime Permutations
71496
50Consecutive Prime Sum
76589