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Problem Archives

The problems archives table shows problems 1 to 872. If you would like to tackle the 10 most recently published problems, go to Recent problems.


ID

TitleSolved By
1Multiples of 3 or 5
992297
2Even Fibonacci Numbers
791462
3Largest Prime Factor
570062
4Largest Palindrome Product
504457
5Smallest Multiple
507377
6Sum Square Difference
510671
710001st Prime
437109
8Largest Product in a Series
366594
9Special Pythagorean Triplet
371624
10Summation of Primes
340961
11Largest Product in a Grid
245186
12Highly Divisible Triangular Number
231737
13Large Sum
237037
14Longest Collatz Sequence
237429
15Lattice Paths
196245
16Power Digit Sum
239633
17Number Letter Counts
159497
18Maximum Path Sum I
152728
19Counting Sundays
141840
20Factorial Digit Sum
207540
21Amicable Numbers
154002
22Names Scores
141603
23Non-Abundant Sums
110378
24Lexicographic Permutations
121103
25$1000$-digit Fibonacci Number
163319
26Reciprocal Cycles
89278
27Quadratic Primes
92712
28Number Spiral Diagonals
113801
29Distinct Powers
111511
30Digit Fifth Powers
116035
31Coin Sums
90400
32Pandigital Products
75806
33Digit Cancelling Fractions
76150
34Digit Factorials
99584
35Circular Primes
89690
36Double-base Palindromes
93840
37Truncatable Primes
78067
38Pandigital Multiples
67039
39Integer Right Triangles
77612
40Champernowne's Constant
84737
41Pandigital Prime
72421
42Coded Triangle Numbers
78760
43Sub-string Divisibility
63772
44Pentagon Numbers
62414
45Triangular, Pentagonal, and Hexagonal
75103
46Goldbach's Other Conjecture
65578
47Distinct Primes Factors
61795
48Self Powers
117812
49Prime Permutations
61667
50Consecutive Prime Sum
66467