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Problem Archives

The problems archives table shows problems 1 to 1001. 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
854491
2Even Fibonacci Numbers
683164
3Largest Prime Factor
514805
4Largest Palindrome Product
455054
5Smallest Multiple
441527
6Sum Square Difference
446496
710 001st Prime
389111
8Largest Product in a Series
331389
9Special Pythagorean Triplet
336896
10Summation of Primes
316262
11Largest Product in a Grid
236933
12Highly Divisible Triangular Number
233254
13Large Sum
234004
14Longest Collatz Sequence
238385
15Lattice Paths
202245
16Power Digit Sum
236710
17Number Letter Counts
169650
18Maximum Path Sum I
164013
19Counting Sundays
153811
20Factorial Digit Sum
206957
21Amicable Numbers
169139
22Names Scores
155874
23Non-Abundant Sums
128554
24Lexicographic Permutations
137686
25$1000$-digit Fibonacci Number
175345
26Reciprocal Cycles
104679
27Quadratic Primes
108197
28Number Spiral Diagonals
126900
29Distinct Powers
127877
30Digit Fifth Powers
132652
31Coin Sums
104452
32Pandigital Products
89042
33Digit Cancelling Fractions
88900
34Digit Factorials
115050
35Circular Primes
103072
36Double-base Palindromes
107611
37Truncatable Primes
91026
38Pandigital Multiples
78214
39Integer Right Triangles
89954
40Champernowne's Constant
96995
41Pandigital Prime
84359
42Coded Triangle Numbers
89960
43Sub-string Divisibility
74345
44Pentagon Numbers
72905
45Triangular, Pentagonal, and Hexagonal
86377
46Goldbach's Other Conjecture
76458
47Distinct Primes Factors
71932
48Self Powers
123060
49Prime Permutations
71536
50Consecutive Prime Sum
76636