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Problem Archives

The problems archives table shows problems 1 to 999. 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
857072
2Even Fibonacci Numbers
685135
3Largest Prime Factor
516001
4Largest Palindrome Product
456081
5Smallest Multiple
442513
6Sum Square Difference
447324
710 001st Prime
389919
8Largest Product in a Series
331901
9Special Pythagorean Triplet
337489
10Summation of Primes
316775
11Largest Product in a Grid
237143
12Highly Divisible Triangular Number
233465
13Large Sum
234202
14Longest Collatz Sequence
238587
15Lattice Paths
202348
16Power Digit Sum
236863
17Number Letter Counts
169702
18Maximum Path Sum I
164009
19Counting Sundays
153794
20Factorial Digit Sum
207008
21Amicable Numbers
169122
22Names Scores
155852
23Non-Abundant Sums
128450
24Lexicographic Permutations
137619
25$1000$-digit Fibonacci Number
175345
26Reciprocal Cycles
104590
27Quadratic Primes
108104
28Number Spiral Diagonals
126821
29Distinct Powers
127828
30Digit Fifth Powers
132587
31Coin Sums
104374
32Pandigital Products
88960
33Digit Cancelling Fractions
88801
34Digit Factorials
114958
35Circular Primes
102999
36Double-base Palindromes
107519
37Truncatable Primes
90927
38Pandigital Multiples
78147
39Integer Right Triangles
89876
40Champernowne's Constant
96941
41Pandigital Prime
84296
42Coded Triangle Numbers
89868
43Sub-string Divisibility
74275
44Pentagon Numbers
72848
45Triangular, Pentagonal, and Hexagonal
86306
46Goldbach's Other Conjecture
76397
47Distinct Primes Factors
71878
48Self Powers
123034
49Prime Permutations
71481
50Consecutive Prime Sum
76583