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Problem Archives

The problems archives table shows problems 1 to 1004. 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
851815
2Even Fibonacci Numbers
681258
3Largest Prime Factor
513732
4Largest Palindrome Product
454147
5Smallest Multiple
440655
6Sum Square Difference
445684
710 001st Prime
388400
8Largest Product in a Series
330977
9Special Pythagorean Triplet
336477
10Summation of Primes
315880
11Largest Product in a Grid
236847
12Highly Divisible Triangular Number
233154
13Large Sum
233923
14Longest Collatz Sequence
238307
15Lattice Paths
202255
16Power Digit Sum
236628
17Number Letter Counts
169709
18Maximum Path Sum I
164124
19Counting Sundays
153891
20Factorial Digit Sum
207060
21Amicable Numbers
169201
22Names Scores
155874
23Non-Abundant Sums
128678
24Lexicographic Permutations
137798
25$1000$-digit Fibonacci Number
175390
26Reciprocal Cycles
104809
27Quadratic Primes
108295
28Number Spiral Diagonals
127008
29Distinct Powers
127967
30Digit Fifth Powers
132778
31Coin Sums
104542
32Pandigital Products
89144
33Digit Cancelling Fractions
89010
34Digit Factorials
115161
35Circular Primes
103162
36Double-base Palindromes
107744
37Truncatable Primes
91116
38Pandigital Multiples
78299
39Integer Right Triangles
90054
40Champernowne's Constant
97082
41Pandigital Prime
84426
42Coded Triangle Numbers
90071
43Sub-string Divisibility
74439
44Pentagon Numbers
72994
45Triangular, Pentagonal, and Hexagonal
86488
46Goldbach's Other Conjecture
76546
47Distinct Primes Factors
72011
48Self Powers
123148
49Prime Permutations
71595
50Consecutive Prime Sum
76728