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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
848770
2Even Fibonacci Numbers
679084
3Largest Prime Factor
512432
4Largest Palindrome Product
453129
5Smallest Multiple
439610
6Sum Square Difference
444660
710 001st Prime
387515
8Largest Product in a Series
330397
9Special Pythagorean Triplet
335833
10Summation of Primes
315339
11Largest Product in a Grid
236618
12Highly Divisible Triangular Number
232945
13Large Sum
233731
14Longest Collatz Sequence
238116
15Lattice Paths
202165
16Power Digit Sum
236455
17Number Letter Counts
169697
18Maximum Path Sum I
164103
19Counting Sundays
153900
20Factorial Digit Sum
207022
21Amicable Numbers
169221
22Names Scores
155903
23Non-Abundant Sums
128763
24Lexicographic Permutations
137856
25$1000$-digit Fibonacci Number
175367
26Reciprocal Cycles
104879
27Quadratic Primes
108376
28Number Spiral Diagonals
127108
29Distinct Powers
128042
30Digit Fifth Powers
132908
31Coin Sums
104609
32Pandigital Products
89208
33Digit Cancelling Fractions
89099
34Digit Factorials
115260
35Circular Primes
103218
36Double-base Palindromes
107844
37Truncatable Primes
91188
38Pandigital Multiples
78350
39Integer Right Triangles
90143
40Champernowne's Constant
97138
41Pandigital Prime
84475
42Coded Triangle Numbers
90171
43Sub-string Divisibility
74511
44Pentagon Numbers
73034
45Triangular, Pentagonal, and Hexagonal
86556
46Goldbach's Other Conjecture
76597
47Distinct Primes Factors
72057
48Self Powers
123178
49Prime Permutations
71651
50Consecutive Prime Sum
76791