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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
861505
2Even Fibonacci Numbers
688510
3Largest Prime Factor
518066
4Largest Palindrome Product
457736
5Smallest Multiple
444145
6Sum Square Difference
449077
710 001st Prime
391253
8Largest Product in a Series
332683
9Special Pythagorean Triplet
338440
10Summation of Primes
317584
11Largest Product in a Grid
237508
12Highly Divisible Triangular Number
233773
13Large Sum
234466
14Longest Collatz Sequence
238870
15Lattice Paths
202468
16Power Digit Sum
237039
17Number Letter Counts
169712
18Maximum Path Sum I
163950
19Counting Sundays
153788
20Factorial Digit Sum
207000
21Amicable Numbers
169068
22Names Scores
155756
23Non-Abundant Sums
128250
24Lexicographic Permutations
137466
25$1000$-digit Fibonacci Number
175358
26Reciprocal Cycles
104425
27Quadratic Primes
107936
28Number Spiral Diagonals
126652
29Distinct Powers
127687
30Digit Fifth Powers
132421
31Coin Sums
104275
32Pandigital Products
88828
33Digit Cancelling Fractions
88631
34Digit Factorials
114766
35Circular Primes
102870
36Double-base Palindromes
107336
37Truncatable Primes
90798
38Pandigital Multiples
78024
39Integer Right Triangles
89726
40Champernowne's Constant
96825
41Pandigital Prime
84172
42Coded Triangle Numbers
89705
43Sub-string Divisibility
74135
44Pentagon Numbers
72720
45Triangular, Pentagonal, and Hexagonal
86146
46Goldbach's Other Conjecture
76265
47Distinct Primes Factors
71753
48Self Powers
122957
49Prime Permutations
71362
50Consecutive Prime Sum
76455