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Problem Archives

The problems archives table shows problems 1 to 1009. 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
846578
2Even Fibonacci Numbers
677515
3Largest Prime Factor
511474
4Largest Palindrome Product
452389
5Smallest Multiple
438851
6Sum Square Difference
443937
710 001st Prime
386950
8Largest Product in a Series
330010
9Special Pythagorean Triplet
335440
10Summation of Primes
315008
11Largest Product in a Grid
236434
12Highly Divisible Triangular Number
232819
13Large Sum
233584
14Longest Collatz Sequence
237993
15Lattice Paths
202120
16Power Digit Sum
236389
17Number Letter Counts
169699
18Maximum Path Sum I
164118
19Counting Sundays
153933
20Factorial Digit Sum
207027
21Amicable Numbers
169249
22Names Scores
155953
23Non-Abundant Sums
128826
24Lexicographic Permutations
137926
25$1000$-digit Fibonacci Number
175421
26Reciprocal Cycles
104976
27Quadratic Primes
108449
28Number Spiral Diagonals
127193
29Distinct Powers
128127
30Digit Fifth Powers
133027
31Coin Sums
104655
32Pandigital Products
89277
33Digit Cancelling Fractions
89182
34Digit Factorials
115355
35Circular Primes
103285
36Double-base Palindromes
107940
37Truncatable Primes
91249
38Pandigital Multiples
78398
39Integer Right Triangles
90209
40Champernowne's Constant
97177
41Pandigital Prime
84525
42Coded Triangle Numbers
90247
43Sub-string Divisibility
74569
44Pentagon Numbers
73097
45Triangular, Pentagonal, and Hexagonal
86631
46Goldbach's Other Conjecture
76646
47Distinct Primes Factors
72105
48Self Powers
123221
49Prime Permutations
71692
50Consecutive Prime Sum
76837