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Problem Archives

The problems archives table shows problems 1 to 997. 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
863305
2Even Fibonacci Numbers
689854
3Largest Prime Factor
518832
4Largest Palindrome Product
458414
5Smallest Multiple
444803
6Sum Square Difference
449702
710 001st Prime
391764
8Largest Product in a Series
332995
9Special Pythagorean Triplet
338784
10Summation of Primes
317877
11Largest Product in a Grid
237623
12Highly Divisible Triangular Number
233893
13Large Sum
234593
14Longest Collatz Sequence
238967
15Lattice Paths
202465
16Power Digit Sum
237094
17Number Letter Counts
169682
18Maximum Path Sum I
163916
19Counting Sundays
153766
20Factorial Digit Sum
206985
21Amicable Numbers
169017
22Names Scores
155683
23Non-Abundant Sums
128173
24Lexicographic Permutations
137385
25$1000$-digit Fibonacci Number
175309
26Reciprocal Cycles
104331
27Quadratic Primes
107859
28Number Spiral Diagonals
126563
29Distinct Powers
127618
30Digit Fifth Powers
132317
31Coin Sums
104197
32Pandigital Products
88746
33Digit Cancelling Fractions
88531
34Digit Factorials
114660
35Circular Primes
102799
36Double-base Palindromes
107217
37Truncatable Primes
90720
38Pandigital Multiples
77955
39Integer Right Triangles
89627
40Champernowne's Constant
96752
41Pandigital Prime
84087
42Coded Triangle Numbers
89619
43Sub-string Divisibility
74058
44Pentagon Numbers
72652
45Triangular, Pentagonal, and Hexagonal
86069
46Goldbach's Other Conjecture
76192
47Distinct Primes Factors
71680
48Self Powers
122932
49Prime Permutations
71293
50Consecutive Prime Sum
76368