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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
848375
2Even Fibonacci Numbers
678803
3Largest Prime Factor
512248
4Largest Palindrome Product
452967
5Smallest Multiple
439460
6Sum Square Difference
444509
710 001st Prime
387411
8Largest Product in a Series
330320
9Special Pythagorean Triplet
335753
10Summation of Primes
315270
11Largest Product in a Grid
236579
12Highly Divisible Triangular Number
232916
13Large Sum
233700
14Longest Collatz Sequence
238086
15Lattice Paths
202144
16Power Digit Sum
236444
17Number Letter Counts
169696
18Maximum Path Sum I
164099
19Counting Sundays
153892
20Factorial Digit Sum
207017
21Amicable Numbers
169218
22Names Scores
155903
23Non-Abundant Sums
128770
24Lexicographic Permutations
137869
25$1000$-digit Fibonacci Number
175368
26Reciprocal Cycles
104897
27Quadratic Primes
108389
28Number Spiral Diagonals
127116
29Distinct Powers
128048
30Digit Fifth Powers
132922
31Coin Sums
104615
32Pandigital Products
89215
33Digit Cancelling Fractions
89107
34Digit Factorials
115269
35Circular Primes
103221
36Double-base Palindromes
107863
37Truncatable Primes
91191
38Pandigital Multiples
78358
39Integer Right Triangles
90149
40Champernowne's Constant
97137
41Pandigital Prime
84480
42Coded Triangle Numbers
90178
43Sub-string Divisibility
74523
44Pentagon Numbers
73046
45Triangular, Pentagonal, and Hexagonal
86573
46Goldbach's Other Conjecture
76605
47Distinct Primes Factors
72062
48Self Powers
123182
49Prime Permutations
71662
50Consecutive Prime Sum
76796