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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
863726
2Even Fibonacci Numbers
690169
3Largest Prime Factor
519014
4Largest Palindrome Product
458558
5Smallest Multiple
444956
6Sum Square Difference
449845
710 001st Prime
391862
8Largest Product in a Series
333065
9Special Pythagorean Triplet
338858
10Summation of Primes
317938
11Largest Product in a Grid
237642
12Highly Divisible Triangular Number
233903
13Large Sum
234613
14Longest Collatz Sequence
238987
15Lattice Paths
202476
16Power Digit Sum
237103
17Number Letter Counts
169688
18Maximum Path Sum I
163911
19Counting Sundays
153765
20Factorial Digit Sum
206991
21Amicable Numbers
169014
22Names Scores
155680
23Non-Abundant Sums
128162
24Lexicographic Permutations
137374
25$1000$-digit Fibonacci Number
175308
26Reciprocal Cycles
104314
27Quadratic Primes
107841
28Number Spiral Diagonals
126543
29Distinct Powers
127605
30Digit Fifth Powers
132294
31Coin Sums
104193
32Pandigital Products
88732
33Digit Cancelling Fractions
88519
34Digit Factorials
114642
35Circular Primes
102790
36Double-base Palindromes
107200
37Truncatable Primes
90708
38Pandigital Multiples
77938
39Integer Right Triangles
89614
40Champernowne's Constant
96740
41Pandigital Prime
84072
42Coded Triangle Numbers
89604
43Sub-string Divisibility
74048
44Pentagon Numbers
72643
45Triangular, Pentagonal, and Hexagonal
86058
46Goldbach's Other Conjecture
76184
47Distinct Primes Factors
71672
48Self Powers
122931
49Prime Permutations
71279
50Consecutive Prime Sum
76355