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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
860917
2Even Fibonacci Numbers
688059
3Largest Prime Factor
517800
4Largest Palindrome Product
457519
5Smallest Multiple
443906
6Sum Square Difference
448845
710 001st Prime
391087
8Largest Product in a Series
332601
9Special Pythagorean Triplet
338329
10Summation of Primes
317489
11Largest Product in a Grid
237470
12Highly Divisible Triangular Number
233739
13Large Sum
234453
14Longest Collatz Sequence
238846
15Lattice Paths
202472
16Power Digit Sum
237046
17Number Letter Counts
169741
18Maximum Path Sum I
163984
19Counting Sundays
153797
20Factorial Digit Sum
207028
21Amicable Numbers
169089
22Names Scores
155786
23Non-Abundant Sums
128305
24Lexicographic Permutations
137506
25$1000$-digit Fibonacci Number
175368
26Reciprocal Cycles
104464
27Quadratic Primes
107979
28Number Spiral Diagonals
126695
29Distinct Powers
127721
30Digit Fifth Powers
132458
31Coin Sums
104299
32Pandigital Products
88848
33Digit Cancelling Fractions
88666
34Digit Factorials
114810
35Circular Primes
102887
36Double-base Palindromes
107377
37Truncatable Primes
90827
38Pandigital Multiples
78052
39Integer Right Triangles
89755
40Champernowne's Constant
96848
41Pandigital Prime
84198
42Coded Triangle Numbers
89739
43Sub-string Divisibility
74159
44Pentagon Numbers
72746
45Triangular, Pentagonal, and Hexagonal
86187
46Goldbach's Other Conjecture
76301
47Distinct Primes Factors
71787
48Self Powers
122982
49Prime Permutations
71388
50Consecutive Prime Sum
76490