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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
847878
2Even Fibonacci Numbers
678426
3Largest Prime Factor
512043
4Largest Palindrome Product
452802
5Smallest Multiple
439272
6Sum Square Difference
444337
710 001st Prime
387264
8Largest Product in a Series
330222
9Special Pythagorean Triplet
335657
10Summation of Primes
315192
11Largest Product in a Grid
236538
12Highly Divisible Triangular Number
232884
13Large Sum
233673
14Longest Collatz Sequence
238048
15Lattice Paths
202135
16Power Digit Sum
236421
17Number Letter Counts
169699
18Maximum Path Sum I
164108
19Counting Sundays
153908
20Factorial Digit Sum
207010
21Amicable Numbers
169221
22Names Scores
155921
23Non-Abundant Sums
128787
24Lexicographic Permutations
137891
25$1000$-digit Fibonacci Number
175395
26Reciprocal Cycles
104922
27Quadratic Primes
108405
28Number Spiral Diagonals
127143
29Distinct Powers
128064
30Digit Fifth Powers
132958
31Coin Sums
104614
32Pandigital Products
89231
33Digit Cancelling Fractions
89128
34Digit Factorials
115289
35Circular Primes
103239
36Double-base Palindromes
107884
37Truncatable Primes
91207
38Pandigital Multiples
78369
39Integer Right Triangles
90168
40Champernowne's Constant
97144
41Pandigital Prime
84489
42Coded Triangle Numbers
90203
43Sub-string Divisibility
74541
44Pentagon Numbers
73055
45Triangular, Pentagonal, and Hexagonal
86584
46Goldbach's Other Conjecture
76617
47Distinct Primes Factors
72077
48Self Powers
123199
49Prime Permutations
71677
50Consecutive Prime Sum
76810