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Problem Archives

The problems archives table shows problems 1 to 1006. 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
849046
2Even Fibonacci Numbers
679287
3Largest Prime Factor
512559
4Largest Palindrome Product
453237
5Smallest Multiple
439714
6Sum Square Difference
444761
710 001st Prime
387601
8Largest Product in a Series
330456
9Special Pythagorean Triplet
335889
10Summation of Primes
315391
11Largest Product in a Grid
236647
12Highly Divisible Triangular Number
232970
13Large Sum
233748
14Longest Collatz Sequence
238132
15Lattice Paths
202175
16Power Digit Sum
236474
17Number Letter Counts
169704
18Maximum Path Sum I
164116
19Counting Sundays
153903
20Factorial Digit Sum
207031
21Amicable Numbers
169216
22Names Scores
155908
23Non-Abundant Sums
128757
24Lexicographic Permutations
137850
25$1000$-digit Fibonacci Number
175372
26Reciprocal Cycles
104876
27Quadratic Primes
108374
28Number Spiral Diagonals
127099
29Distinct Powers
128037
30Digit Fifth Powers
132901
31Coin Sums
104608
32Pandigital Products
89202
33Digit Cancelling Fractions
89091
34Digit Factorials
115254
35Circular Primes
103216
36Double-base Palindromes
107834
37Truncatable Primes
91182
38Pandigital Multiples
78347
39Integer Right Triangles
90135
40Champernowne's Constant
97136
41Pandigital Prime
84470
42Coded Triangle Numbers
90164
43Sub-string Divisibility
74504
44Pentagon Numbers
73030
45Triangular, Pentagonal, and Hexagonal
86554
46Goldbach's Other Conjecture
76595
47Distinct Primes Factors
72054
48Self Powers
123178
49Prime Permutations
71647
50Consecutive Prime Sum
76790