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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
850276
2Even Fibonacci Numbers
680151
3Largest Prime Factor
513074
4Largest Palindrome Product
453662
5Smallest Multiple
440140
6Sum Square Difference
445210
710 001st Prime
387968
8Largest Product in a Series
330716
9Special Pythagorean Triplet
336156
10Summation of Primes
315606
11Largest Product in a Grid
236738
12Highly Divisible Triangular Number
233055
13Large Sum
233831
14Longest Collatz Sequence
238230
15Lattice Paths
202220
16Power Digit Sum
236558
17Number Letter Counts
169717
18Maximum Path Sum I
164125
19Counting Sundays
153897
20Factorial Digit Sum
207057
21Amicable Numbers
169209
22Names Scores
155892
23Non-Abundant Sums
128723
24Lexicographic Permutations
137830
25$1000$-digit Fibonacci Number
175396
26Reciprocal Cycles
104841
27Quadratic Primes
108335
28Number Spiral Diagonals
127063
29Distinct Powers
127997
30Digit Fifth Powers
132842
31Coin Sums
104583
32Pandigital Products
89170
33Digit Cancelling Fractions
89053
34Digit Factorials
115206
35Circular Primes
103189
36Double-base Palindromes
107782
37Truncatable Primes
91146
38Pandigital Multiples
78320
39Integer Right Triangles
90093
40Champernowne's Constant
97114
41Pandigital Prime
84445
42Coded Triangle Numbers
90114
43Sub-string Divisibility
74468
44Pentagon Numbers
73009
45Triangular, Pentagonal, and Hexagonal
86526
46Goldbach's Other Conjecture
76573
47Distinct Primes Factors
72028
48Self Powers
123164
49Prime Permutations
71617
50Consecutive Prime Sum
76754