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Problem Archives

The problems archives table shows problems 1 to 1008. 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
846558
2Even Fibonacci Numbers
677506
3Largest Prime Factor
511465
4Largest Palindrome Product
452383
5Smallest Multiple
438844
6Sum Square Difference
443930
710 001st Prime
386939
8Largest Product in a Series
330004
9Special Pythagorean Triplet
335436
10Summation of Primes
315004
11Largest Product in a Grid
236429
12Highly Divisible Triangular Number
232814
13Large Sum
233580
14Longest Collatz Sequence
237989
15Lattice Paths
202119
16Power Digit Sum
236387
17Number Letter Counts
169696
18Maximum Path Sum I
164114
19Counting Sundays
153929
20Factorial Digit Sum
207022
21Amicable Numbers
169246
22Names Scores
155952
23Non-Abundant Sums
128823
24Lexicographic Permutations
137923
25$1000$-digit Fibonacci Number
175418
26Reciprocal Cycles
104975
27Quadratic Primes
108447
28Number Spiral Diagonals
127190
29Distinct Powers
128125
30Digit Fifth Powers
133023
31Coin Sums
104653
32Pandigital Products
89276
33Digit Cancelling Fractions
89181
34Digit Factorials
115354
35Circular Primes
103283
36Double-base Palindromes
107940
37Truncatable Primes
91249
38Pandigital Multiples
78398
39Integer Right Triangles
90209
40Champernowne's Constant
97176
41Pandigital Prime
84525
42Coded Triangle Numbers
90244
43Sub-string Divisibility
74568
44Pentagon Numbers
73095
45Triangular, Pentagonal, and Hexagonal
86629
46Goldbach's Other Conjecture
76644
47Distinct Primes Factors
72104
48Self Powers
123221
49Prime Permutations
71691
50Consecutive Prime Sum
76836