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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
861543
2Even Fibonacci Numbers
688528
3Largest Prime Factor
518076
4Largest Palindrome Product
457744
5Smallest Multiple
444155
6Sum Square Difference
449087
710 001st Prime
391263
8Largest Product in a Series
332688
9Special Pythagorean Triplet
338446
10Summation of Primes
317591
11Largest Product in a Grid
237514
12Highly Divisible Triangular Number
233780
13Large Sum
234475
14Longest Collatz Sequence
238878
15Lattice Paths
202471
16Power Digit Sum
237047
17Number Letter Counts
169715
18Maximum Path Sum I
163953
19Counting Sundays
153790
20Factorial Digit Sum
207008
21Amicable Numbers
169075
22Names Scores
155760
23Non-Abundant Sums
128255
24Lexicographic Permutations
137468
25$1000$-digit Fibonacci Number
175362
26Reciprocal Cycles
104427
27Quadratic Primes
107943
28Number Spiral Diagonals
126654
29Distinct Powers
127689
30Digit Fifth Powers
132421
31Coin Sums
104275
32Pandigital Products
88828
33Digit Cancelling Fractions
88633
34Digit Factorials
114770
35Circular Primes
102871
36Double-base Palindromes
107344
37Truncatable Primes
90799
38Pandigital Multiples
78028
39Integer Right Triangles
89729
40Champernowne's Constant
96830
41Pandigital Prime
84175
42Coded Triangle Numbers
89709
43Sub-string Divisibility
74138
44Pentagon Numbers
72725
45Triangular, Pentagonal, and Hexagonal
86150
46Goldbach's Other Conjecture
76269
47Distinct Primes Factors
71756
48Self Powers
122962
49Prime Permutations
71364
50Consecutive Prime Sum
76457