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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
992299
2Even Fibonacci Numbers
791464
3Largest Prime Factor
570064
4Largest Palindrome Product
504459
5Smallest Multiple
507380
6Sum Square Difference
510674
710001st Prime
437111
8Largest Product in a Series
366595
9Special Pythagorean Triplet
371625
10Summation of Primes
340962
11Largest Product in a Grid
245187
12Highly Divisible Triangular Number
231738
13Large Sum
237038
14Longest Collatz Sequence
237430
15Lattice Paths
196246
16Power Digit Sum
239633
17Number Letter Counts
159497
18Maximum Path Sum I
152728
19Counting Sundays
141842
20Factorial Digit Sum
207541
21Amicable Numbers
154003
22Names Scores
141603
23Non-Abundant Sums
110378
24Lexicographic Permutations
121103
25$1000$-digit Fibonacci Number
163320
26Reciprocal Cycles
89279
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
77613
40Champernowne's Constant
84738
41Pandigital Prime
72421
42Coded Triangle Numbers
78760
43Sub-string Divisibility
63772
44Pentagon Numbers
62414
45Triangular, Pentagonal, and Hexagonal
75103
46Goldbach's Other Conjecture
65579
47Distinct Primes Factors
61795
48Self Powers
117812
49Prime Permutations
61667
50Consecutive Prime Sum
66467