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Problem Archives

The problems archives table shows problems 1 to 1008. 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
846832
2Even Fibonacci Numbers
677685
3Largest Prime Factor
511586
4Largest Palindrome Product
452451
5Smallest Multiple
438926
6Sum Square Difference
444016
710 001st Prime
387006
8Largest Product in a Series
330041
9Special Pythagorean Triplet
335474
10Summation of Primes
315042
11Largest Product in a Grid
236455
12Highly Divisible Triangular Number
232832
13Large Sum
233595
14Longest Collatz Sequence
237999
15Lattice Paths
202112
16Power Digit Sum
236396
17Number Letter Counts
169697
18Maximum Path Sum I
164121
19Counting Sundays
153927
20Factorial Digit Sum
207025
21Amicable Numbers
169248
22Names Scores
155955
23Non-Abundant Sums
128816
24Lexicographic Permutations
137914
25$1000$-digit Fibonacci Number
175416
26Reciprocal Cycles
104957
27Quadratic Primes
108438
28Number Spiral Diagonals
127182
29Distinct Powers
128111
30Digit Fifth Powers
133007
31Coin Sums
104648
32Pandigital Products
89268
33Digit Cancelling Fractions
89168
34Digit Factorials
115346
35Circular Primes
103274
36Double-base Palindromes
107930
37Truncatable Primes
91239
38Pandigital Multiples
78392
39Integer Right Triangles
90199
40Champernowne's Constant
97168
41Pandigital Prime
84518
42Coded Triangle Numbers
90238
43Sub-string Divisibility
74565
44Pentagon Numbers
73088
45Triangular, Pentagonal, and Hexagonal
86621
46Goldbach's Other Conjecture
76641
47Distinct Primes Factors
72098
48Self Powers
123225
49Prime Permutations
71686
50Consecutive Prime Sum
76829