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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
860142
2Even Fibonacci Numbers
687456
3Largest Prime Factor
517435
4Largest Palindrome Product
457219
5Smallest Multiple
443632
6Sum Square Difference
448570
710 001st Prime
390859
8Largest Product in a Series
332463
9Special Pythagorean Triplet
338170
10Summation of Primes
317340
11Largest Product in a Grid
237388
12Highly Divisible Triangular Number
233671
13Large Sum
234401
14Longest Collatz Sequence
238774
15Lattice Paths
202456
16Power Digit Sum
237014
17Number Letter Counts
169721
18Maximum Path Sum I
163981
19Counting Sundays
153788
20Factorial Digit Sum
207028
21Amicable Numbers
169092
22Names Scores
155804
23Non-Abundant Sums
128338
24Lexicographic Permutations
137540
25$1000$-digit Fibonacci Number
175370
26Reciprocal Cycles
104496
27Quadratic Primes
108000
28Number Spiral Diagonals
126719
29Distinct Powers
127745
30Digit Fifth Powers
132489
31Coin Sums
104312
32Pandigital Products
88878
33Digit Cancelling Fractions
88697
34Digit Factorials
114854
35Circular Primes
102920
36Double-base Palindromes
107418
37Truncatable Primes
90851
38Pandigital Multiples
78074
39Integer Right Triangles
89783
40Champernowne's Constant
96864
41Pandigital Prime
84224
42Coded Triangle Numbers
89774
43Sub-string Divisibility
74191
44Pentagon Numbers
72771
45Triangular, Pentagonal, and Hexagonal
86214
46Goldbach's Other Conjecture
76326
47Distinct Primes Factors
71806
48Self Powers
122989
49Prime Permutations
71409
50Consecutive Prime Sum
76518