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Problem Archives

The problems archives table shows problems 1 to 1005. 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
850735
2Even Fibonacci Numbers
680499
3Largest Prime Factor
513251
4Largest Palindrome Product
453789
5Smallest Multiple
440265
6Sum Square Difference
445310
710 001st Prime
388072
8Largest Product in a Series
330779
9Special Pythagorean Triplet
336215
10Summation of Primes
315661
11Largest Product in a Grid
236757
12Highly Divisible Triangular Number
233060
13Large Sum
233853
14Longest Collatz Sequence
238249
15Lattice Paths
202234
16Power Digit Sum
236561
17Number Letter Counts
169699
18Maximum Path Sum I
164108
19Counting Sundays
153878
20Factorial Digit Sum
207035
21Amicable Numbers
169187
22Names Scores
155875
23Non-Abundant Sums
128692
24Lexicographic Permutations
137805
25$1000$-digit Fibonacci Number
175381
26Reciprocal Cycles
104825
27Quadratic Primes
108309
28Number Spiral Diagonals
127036
29Distinct Powers
127978
30Digit Fifth Powers
132807
31Coin Sums
104562
32Pandigital Products
89151
33Digit Cancelling Fractions
89030
34Digit Factorials
115182
35Circular Primes
103173
36Double-base Palindromes
107764
37Truncatable Primes
91126
38Pandigital Multiples
78308
39Integer Right Triangles
90072
40Champernowne's Constant
97098
41Pandigital Prime
84427
42Coded Triangle Numbers
90092
43Sub-string Divisibility
74450
44Pentagon Numbers
73000
45Triangular, Pentagonal, and Hexagonal
86501
46Goldbach's Other Conjecture
76561
47Distinct Primes Factors
72014
48Self Powers
123153
49Prime Permutations
71608
50Consecutive Prime Sum
76736