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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
852032
2Even Fibonacci Numbers
681397
3Largest Prime Factor
513816
4Largest Palindrome Product
454221
5Smallest Multiple
440752
6Sum Square Difference
445750
710 001st Prime
388458
8Largest Product in a Series
331010
9Special Pythagorean Triplet
336513
10Summation of Primes
315906
11Largest Product in a Grid
236848
12Highly Divisible Triangular Number
233146
13Large Sum
233907
14Longest Collatz Sequence
238288
15Lattice Paths
202240
16Power Digit Sum
236611
17Number Letter Counts
169695
18Maximum Path Sum I
164106
19Counting Sundays
153878
20Factorial Digit Sum
207039
21Amicable Numbers
169189
22Names Scores
155864
23Non-Abundant Sums
128653
24Lexicographic Permutations
137775
25$1000$-digit Fibonacci Number
175376
26Reciprocal Cycles
104789
27Quadratic Primes
108288
28Number Spiral Diagonals
126996
29Distinct Powers
127961
30Digit Fifth Powers
132755
31Coin Sums
104535
32Pandigital Products
89130
33Digit Cancelling Fractions
89000
34Digit Factorials
115144
35Circular Primes
103144
36Double-base Palindromes
107725
37Truncatable Primes
91101
38Pandigital Multiples
78285
39Integer Right Triangles
90047
40Champernowne's Constant
97066
41Pandigital Prime
84414
42Coded Triangle Numbers
90060
43Sub-string Divisibility
74427
44Pentagon Numbers
72979
45Triangular, Pentagonal, and Hexagonal
86471
46Goldbach's Other Conjecture
76528
47Distinct Primes Factors
71992
48Self Powers
123130
49Prime Permutations
71586
50Consecutive Prime Sum
76711